Hypertext Transfer Protocol Secure is an extension of the Hypertext Transfer Protocol. It is used for secure communication over a computer network, is used on the Internet. In HTTPS, the communication protocol is encrypted using Transport Layer Security, or its predecessor, Secure Sockets Layer; the protocol is therefore often referred to as HTTP over TLS, or HTTP over SSL. The principal motivation for HTTPS is authentication of the accessed website and protection of the privacy and integrity of the exchanged data while in transit, it protects against man-in-the-middle attacks. The bidirectional encryption of communications between a client and server protects against eavesdropping and tampering of the communication. In practice, this provides a reasonable assurance that one is communicating without interference by attackers with the website that one intended to communicate with, as opposed to an impostor. HTTPS connections were used for payment transactions on the World Wide Web, e-mail and for sensitive transactions in corporate information systems.
Since 2018, HTTPS is used more by web users than the original non-secure HTTP to protect page authenticity on all types of websites. The Uniform Resource Identifier scheme HTTPS has identical usage syntax to the HTTP scheme. However, HTTPS signals the browser to use an added encryption layer of SSL/TLS to protect the traffic. SSL/TLS is suited for HTTP, since it can provide some protection if only one side of the communication is authenticated; this is the case with HTTP transactions over the Internet, where only the server is authenticated. HTTPS creates a secure channel over an insecure network; this ensures reasonable protection from eavesdroppers and man-in-the-middle attacks, provided that adequate cipher suites are used and that the server certificate is verified and trusted. Because HTTPS piggybacks HTTP on top of TLS, the entirety of the underlying HTTP protocol can be encrypted; this includes the request URL, query parameters and cookies. However, because host addresses and port numbers are part of the underlying TCP/IP protocols, HTTPS cannot protect their disclosure.
In practice this means that on a configured web server, eavesdroppers can infer the IP address and port number of the web server that one is communicating with, as well as the amount and duration of the communication, though not the content of the communication. Web browsers know how to trust HTTPS websites based on certificate authorities that come pre-installed in their software. Certificate authorities are in this way being trusted by web browser creators to provide valid certificates. Therefore, a user should trust an HTTPS connection to a website if and only if all of the following are true: The user trusts that the browser software implements HTTPS with pre-installed certificate authorities; the user trusts the certificate authority to vouch only for legitimate websites. The website provides a valid certificate; the certificate identifies the website. The user trusts. HTTPS is important over insecure networks, as anyone on the same local network can packet-sniff and discover sensitive information not protected by HTTPS.
Additionally, many free to use and paid WLAN networks engage in packet injection in order to serve their own ads on webpages. However, this can be exploited maliciously in many ways, such as injecting malware onto webpages and stealing users' private information. HTTPS is very important for connections over the Tor anonymity network, as malicious Tor nodes can damage or alter the contents passing through them in an insecure fashion and inject malware into the connection; this is one reason why the Electronic Frontier Foundation and the Tor project started the development of HTTPS Everywhere, included in the Tor Browser Bundle. As more information is revealed about global mass surveillance and criminals stealing personal information, the use of HTTPS security on all websites is becoming important regardless of the type of Internet connection being used. While metadata about individual pages that a user visits is not sensitive, when combined, they can reveal a lot about the user and compromise the user's privacy.
Deploying HTTPS allows the use of HTTP/2, that are new generations of HTTP, designed to reduce page load times and latency. It is recommended to use HTTP Strict Transport Security with HTTPS to protect users from man-in-the-middle attacks SSL stripping. HTTPS should not be confused with the little-used Secure HTTP specified in RFC 2660; as of April 2018, 33.2% of Alexa top 1,000,000 websites use HTTPS as default, 57.1% of the Internet's 137,971 most popular websites have a secure implementation of HTTPS, 70% of page loads use HTTPS. Most browsers display a warning. Older browsers, when connecting to a site wit
Telia Company AB is a Swedish dominant telephone company and mobile network operator present in Sweden, Norway, Lithuania and Estonia. The company has operations in other countries in Northern and Eastern Europe, in Central Asia and South Asia, with a total of 182.1 million mobile customers. It is headquartered in Stockholm and its stock is traded on the Stockholm Stock Exchange and on the Helsinki Stock Exchange. Telia Company in its current form was first established as TeliaSonera, as the result of a 2002 merger between the Swedish and Finnish telecommunications companies and Sonera; this merger followed shortly after Telia's failed merger attempt with Norwegian telecommunications company Telenor, now its chief competitor in the Nordic countries. Before privatisation, Telia was a state telephone monopoly. Sonera on the other hand had a monopoly only on trunk network calls, while most of local telecommunication was provided by telephone cooperatives; the separate brand names Telia and Sonera have continued to be used in the Swedish and Finnish markets respectively.
Of the stock, 37.3% is owned by the Swedish government, the rest by institutions and private investors worldwide. The Finnish government had 3.2% of shares, but disposed them in February 2018. The Swedish Kungl. Telegrafverket was founded in 1853, when the first electric telegraph line was established between Stockholm and Uppsala. Allmänna Telefon found an equipment supplier in Lars Magnus Ericsson. In this early competition, Telegrafverket with its brand Rikstelefon was a latecomer. However, by securing a national monopoly on long distance telephone lines, it was able with time to control and take over the local networks of growing private telephone companies. A de facto telephone monopoly position was reached around 1920, never needed legal sanction. In 1953 the name was modernised to Televerket. On 1 July 1992 this huge government agency's regulating functions was split off into the Swedish Post and Telecom Authority, with similar functions as the Federal Communications Commission of the United States.
The operation of the state radio and TV broadcast network was spun off into a company named Teracom. On 1 July 1993 the remaining telephone and mobile network operator was transformed into a government-owned shareholding company, named Telia AB. At the height of the dot-com bubble, on 13 June 2000, close to one-third of Telia's shares were introduced on the Stockholm Stock Exchange. In the 1980s, Televerket was a pioneering mobile network operator with the NMT system, followed in the 1990s by GSM. Private competition in analogue mobile phone systems had broken the telephone monopoly, the growing internet allowed more opportunities for competitors; the most important of Telia's Swedish competitors in these areas has been Tele2. When PTS awarded four licenses for the 3rd generation mobile networks in December 2000, Telia was not among the winners, but established an agreement to build a 3G network jointly with Tele2 using Tele2's licence. SUNAB was founded as the jointly owned company that would in turn build and operate the joint 3G network.
In December 2018, Telia in cooperation with Ericsson has launched the first 5G network at KTH Royal Institute of Technology in Stockholm. The history of Sonera dates back to 1917. In 1927, the telegraph agency was merged with the Finnish Post to form a new agency and Telegraph Agency; this agency governed all long distance and international calls until 1994, when competitors were allowed to enter the Finnish market. In the same year, the Post and Telegraph Agency was divided to form two companies, Suomen Posti Oy, Telecom Finland Oy. Telecom Finland changed its name to Sonera in 1998. During the run up to the 2006 general election the Swedish liberal-conservative Alliance stated as one of its policy aims to reduce government ownership in commercial entities, to sell its stake in TeliaSonera; the Alliance formed a coalition government. The sale of TeliaSonera was however presented to the parliament only after the next election in 2010, when the Alliance lost its majority but stayed on as a minority administration.
On 16 March 2011 the Alliance administration lost a parliamentary vote on sale of publicly owned commercial entities, including TeliaSonera, when a coalition of all opposition parties - the Left Party, Social Democratic Party, Green Party and Sweden Democrats - united against the Alliance. In the beginning of 2008, TeliaSonera announced measures to save nearly 500 million Euros which would include 2900 redundancies: 2000 from Sweden and 900 from Finland. France Télécom proposed a 33 billion Euro acquisition offer for TeliaSonera on 5 June 2008, promptly rejected by the company's board. On 20 July 2018, Telia Company announced the acquisition proposal of Bonnier Broadcasting Group from Bonnier Group for 9.2 billion SEK, thus owning TV4 AB, MTV Oy and C More Entertainment. The acquisition is expected to end in the second half of 2019, following regulatory approval. TeliaSonera International Carrier is a tier 1 carrier. Telia Company is now the largest Nordic and Baltic fixed-voice and mobile operator by revenue and customer base.
It operates Europe's largest and fastest-growing wholesale IP backbone and is the 10th-largest global mobile group by consolidated customers (including ownership stakes in Turkce
An operating system is system software that manages computer hardware and software resources and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may include accounting software for cost allocation of processor time, mass storage and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is executed directly by the hardware and makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer – from cellular phones and video game consoles to web servers and supercomputers; the dominant desktop operating system is Microsoft Windows with a market share of around 82.74%. MacOS by Apple Inc. is in second place, the varieties of Linux are collectively in third place. In the mobile sector, use in 2017 is up to 70% of Google's Android and according to third quarter 2016 data, Android on smartphones is dominant with 87.5 percent and a growth rate 10.3 percent per year, followed by Apple's iOS with 12.1 percent and a per year decrease in market share of 5.2 percent, while other operating systems amount to just 0.3 percent.
Linux distributions are dominant in supercomputing sectors. Other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications. A single-tasking system can only run one program at a time, while a multi-tasking operating system allows more than one program to be running in concurrency; this is achieved by time-sharing, where the available processor time is divided between multiple processes. These processes are each interrupted in time slices by a task-scheduling subsystem of the operating system. Multi-tasking may be characterized in co-operative types. In preemptive multitasking, the operating system slices the CPU time and dedicates a slot to each of the programs. Unix-like operating systems, such as Solaris and Linux—as well as non-Unix-like, such as AmigaOS—support preemptive multitasking. Cooperative multitasking is achieved by relying on each process to provide time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking.
32-bit versions of both Windows NT and Win9x, used preemptive multi-tasking. Single-user operating systems have no facilities to distinguish users, but may allow multiple programs to run in tandem. A multi-user operating system extends the basic concept of multi-tasking with facilities that identify processes and resources, such as disk space, belonging to multiple users, the system permits multiple users to interact with the system at the same time. Time-sharing operating systems schedule tasks for efficient use of the system and may include accounting software for cost allocation of processor time, mass storage and other resources to multiple users. A distributed operating system manages a group of distinct computers and makes them appear to be a single computer; the development of networked computers that could be linked and communicate with each other gave rise to distributed computing. Distributed computations are carried out on more than one machine; when computers in a group work in cooperation, they form a distributed system.
In an OS, distributed and cloud computing context, templating refers to creating a single virtual machine image as a guest operating system saving it as a tool for multiple running virtual machines. The technique is used both in virtualization and cloud computing management, is common in large server warehouses. Embedded operating systems are designed to be used in embedded computer systems, they are designed to operate on small machines like PDAs with less autonomy. They are able to operate with a limited number of resources, they are compact and efficient by design. Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is an operating system that guarantees to process events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, it uses specialized scheduling algorithms so that a deterministic nature of behavior is achieved. An event-driven system switches between tasks based on their priorities or external events while time-sharing operating systems switch tasks based on clock interrupts.
A library operating system is one in which the services that a typical operating system provides, such as networking, are provided in the form of libraries and composed with the application and configuration code to construct a unikernel: a specialized, single address space, machine image that can be deployed to cloud or embedded environments. Early computers were built to perform a series of single tasks, like a calculator. Basic operating system features were developed in the 1950s, such as resident monitor functions that could automatically run different programs in succession to speed up processing. Operating systems did not exist in their more complex forms until the early 1960s. Hardware features were added, that enabled use of runtime libraries and parallel processing; when personal computers became popular in the 1980s, operating systems were made for them similar in concept to those used on larger computers. In the 1940s, the earliest electronic digital systems had no operating systems.
Electronic systems of this time were programmed on rows of mechanical switches or by jumper wires on plug boards. These were special-purpose systems that, for example, generated ballistics tables for the military or controlled the pri
Private browsing, privacy mode or incognito mode is a privacy feature in some web browsers to disable browsing history and the web cache. This allows a person to browse the Web without storing local data that could be retrieved at a date. Privacy mode will disable the storage of data in cookies and Flash cookies; this privacy protection is only within the browser application as it may leave traces on the hard drive and memory of the device, or via websites by associating the IP address at the web server. The earliest reference to private browsing was in May 2005, was used to discuss the privacy features in the Safari browser bundled with Mac OS X Tiger; the feature has since been adopted in other browsers, led to popularization of the term in 2008 by mainstream news outlets and computing websites when discussing beta versions of Internet Explorer 8. However, privacy modes operate as shields because browsers do not remove all data from the cache after the session. Plug-ins, like Silverlight, are able to set cookies.
The common web browser plugin Adobe Flash Player began supporting privacy mode in Chrome, Internet Explorer, Safari with the release of version 10.1 in June 2010.. Some browsers allow users to select the privacy mode for single tabs, whereas others create a more isolated environment protected by password and cryptography. Private browsing has multiple uses, including: Reducing history, including autofill and personal information. Performing "pure searches" that are not influenced by prior browsing history or networks or friends' recommendations, which may weight and more rank certain results than others. Preventing accidental saving of login credentials to accounts. Signing into multiple accounts via multiple tabs. Testing websites. Preventing other users of the computer from finding one's search history. Viewing explicit material without outside knowledge; the Mozilla Foundation performed a study about the user behavior when the feature is switched on and how long the session lasts. The results were that most sessions last only about 10 minutes, though there are periods where activation increases.
Private browsing is known by different names in different browsers. In 2012, Brazilian researchers published the results of a research project where they applied forensic techniques to extract information about the users browsing activities on Internet Explorer and Firefox browsers with their private mode enabled, they were able to collect enough data to identify pages visited and partially reconstruct them. This research was extended to include Chrome and Safari browsers; the gathered data proved that browsers' private mode implementations are not able to hide users' browsing activities and that browsers in private mode leave traces of activities in caching structures and files related to the paging process of the operating system. Another independent security analysis, performed by a group of researchers at Newcastle University in 2014, shows a range of security vulnerabilities in the implementation of the private mode across four major browsers; the results are summarized below. Browser extensions are potential threats to the user privacy.
By design, existing browsers choose to enable extensions in the private mode by default. This however allows an installed extension to secretly record the visited websites without the user's awareness. Newer versions of Chrome disable extensions in the private mode by default, but allow the private and the normal modes to run in parallel; this makes it possible for an installed extension in the normal mode to learn the user activities in the private mode by measuring the usage of shared computing resources. Data erasure by the browser alone is found to be insufficient. For example, the records of visited websites during the private session can be retained in memory for a long time after the private session is closed. In addition, the visited website records are kept by the operating system in the local DNS cache. Furthermore, the modified timestamps of certain profile files saved on the disk may reveal if the private mode was turned on and when it was turned on. Software bugs present in some browsers are found to degrade the security of the private mode.
For example, in some earlier versions of Safari, the browser retained private browsing history records if the browser program was not closed or if the user acted to add a bookmark within the private mode. Depending on whether the session is in the private or the normal mode, web browsers exhibit different user interfaces and traffic characteristics; this allows a remote website to tell if the user is in the private mode, for example, by checking the color of the hyperlinks or measuring the time of writing cookies. In 2010, professors at Stanford University found that while Firefox won't record your history during a private browsing session, it still records the sites on which you've installed SSL certificates and allows specific permissions. If you download an SSL certificate from a website or told that site to stop displaying pop-ups and downloading cookies, all of that information is still stored on Firefox. In 2015, researchers from Pennsylvania State University found that a cons
Wireless Application Protocol
Wireless Application Protocol is a technical standard for accessing information over a mobile wireless network. A WAP browser is a web browser for mobile devices such as mobile phones. Introduced with much hype in 1999, WAP achieved some popularity in the early 2000s, but by the 2010s it had been superseded by more modern standards. Most modern handset internet browsers now support HTML, so they do not need to use WAP markup for web page compatibility, therefore, most are no longer able to render and display pages written in WML, WAP's markup language. Before the introduction of WAP, mobile service providers had limited opportunities to offer interactive data services, but needed interactivity to support Internet and Web applications such as email, stock prices and sports headlines; the Japanese i-mode system offered another major competing wireless data protocol. The WAP standard described a protocol suite or stack allowing the interoperability of WAP equipment and software with different network technologies, such as GSM and IS-95.
The bottom-most protocol in the suite, the Wireless Datagram Protocol, functions as an adaptation layer that makes every data network look a bit like UDP to the upper layers by providing unreliable transport of data with two 16-bit port numbers. All the upper layers view WDP as one and the same protocol, which has several "technical realizations" on top of other "data bearers" such as SMS, USSD, etc. On native IP bearers such as GPRS, UMTS packet-radio service, or PPP on top of a circuit-switched data connection, WDP is in fact UDP. WTLS, an optional layer, provides a public-key cryptography-based security mechanism similar to TLS. WTP provides transaction support adapted to the wireless world. WTP supports more than TCP the problem of packet loss, which occurs in 2G wireless technologies in most radio conditions, but is misinterpreted by TCP as network congestion. One can think of WSP as a compressed version of HTTP; this protocol suite allows a terminal to transmit requests that have an HTTP or HTTPS equivalent to a WAP gateway.
The Wireless Application Environment space defines application-specific markup languages. For WAP version 1. X, the primary language of the WAE is Wireless Markup Language. In WAP 2.0, the primary markup language is XHTML Mobile Profile. WAP Push was incorporated into the specification to allow the WAP content to be pushed to the mobile handset with minimal user intervention. A WAP Push is a specially encoded message which includes a link to a WAP address. WAP Push was specified on top of Wireless Datagram Protocol. Most GSM networks have a wide range of modified processors, but GPRS activation from the network is not supported, so WAP Push messages have to be delivered on top of the SMS bearer. On receiving a WAP Push, a WAP 1.2 -enabled handset will automatically give the user the option to access the WAP content. This is known as WAP Push SI. A variant, known as WAP Push SL, directly opens the browser to display the WAP content, without user interaction. Since this behaviour raises security concerns, some handsets handle WAP Push SL messages in the same way as SI, by providing user interaction.
The network entity that processes WAP Pushes and delivers them over an IP or SMS Bearer is known as a Push Proxy Gateway. A re-engineered 2.0 version was released in 2002. It uses a cut-down version of XHTML with end-to-end HTTP, dropping the gateway and custom protocol suite used to communicate with it. A WAP gateway can be used in conjunction with WAP 2.0. The WAP gateway's role would shift from one of translation to adding additional information to each request; this would be configured by the operator and could include telephone numbers, billing information, handset information. Mobile devices process XHTML Mobile Profile, the markup language defined in WAP 2.0. It is a superset of XHTML Basic. A version of Cascading Style Sheets called WAP CSS is supported by XHTML MP. Multimedia Messaging Service is a combination of WAP and SMS allowing for sending of picture messages; the WAP Forum was founded in 1998 by Ericsson, Motorola and Unwired Planet. It aimed to bring together the various wireless technologies in a standardised protocol.
In 2002 the WAP Forum was consolidated into Open Mobile Alliance. The first company to launch a WAP site was Dutch mobile phone operator Telfort BV in October 1999; the site was developed as a side project by Christopher Bee and Euan McLeod and launched with the debut of the Nokia 7110. Marketers hyped WAP at the time of its introduction, leading users to expect WAP to have the performance of fixed Internet access. BT Cellnet, one of the UK telecoms, ran an advertising campaign depicting a cartoon WAP user surfing through a Neuromancer-like "information space". In terms of speed, ease of use and interoperability, the reality fell far short of expectations when the first handsets became available in 1999; this led to the wide usage of sardonic phrases such as "Worthless Application Protocol", "Wait And Pay", WAPlash. Between 2003 and 2004 WAP made a stronger resurgence with the introduction of wireless services. Operator revenues were generated by transfer of GPRS and UMTS data, a different bus
WAP 2.0 specifies XHTML Mobile Profile plus WAP CSS, subsets of the W3C's standard XHTML and CSS with minor mobile extensions. Newer mobile browsers are full-featured Web browsers capable of HTML, CSS, ECMAScript, as well as mobile technologies such as WML, i-mode HTML, or cHTML. To accommodate small screens, they use Post-WIMP interfaces; the first mobile browser for a PDA was PocketWeb for the Apple Newton created at TecO in 1994, followed by the first commercial product NetHopper released in August 1996. The so-called "microbrowser" technologies such as WAP, NTTDocomo's i-mode platform and Openwave's HDML platform fueled the first wave of interest in wireless data services; the first deployment of a mobile browser on a mobile phone was in 1997 when Unwired Planet put their "UP. Browser" on AT&T handsets to give users access to HDML content. A British company, STNC Ltd. developed a mobile browser in 1997, intended to present the entire device UI. The demonstration platform for this mobile browser had 1 MIPS total processing power.
This was a single core platform, running the GSM stack on the same processor as the application stack. In 1999 STNC was acquired by Microsoft and HitchHiker became Microsoft Mobile Explorer 2.0, not related to the primitive Microsoft Mobile Explorer 1.0. HitchHiker is believed to be the first mobile browser with a unified rendering model, handling HTML and WAP along with ECMAScript, WMLScript, POP3 and IMAP mail in a single client. Although it was not used, it was possible to combine HTML and WAP in the same pages although this would render the pages invalid for any other device. Mobile Explorer 2.0 was available on the Benefon Q, Sony CMD-Z5, CMD-J5, CMD-MZ5, CMD-J6, CMD-Z7, CMD-J7 and CMD-J70. With the addition of a messaging kernel and a driver model, this was powerful enough to be the operating system for certain embedded devices. One such device was the Amstrad e-m@iler and e-m@iler 2; this code formed the basis for MME3. Multiple companies offered browsers for the Palm OS platform; the first HTML browser for Palm OS 1.0 was HandWeb by Smartcode software, released in 1997.
HandWeb included its own TCP/IP stack, Smartcode was acquired by Palm in 1999. Mobile browsers for the Palm OS platform multiplied after the release of Palm OS 2.0, which included a TCP/IP stack. A freeware browser for the Palm OS was Palmscape, written in 1998 by Kazuho Oku in Japan, who went on to found Ilinx. Still in limited use as late as 2003. Qualcomm developed the Eudora Web browser, launched it with the Palm OS based QCP smartphone. ProxiWeb was a proxy-based Web browsing solution, developed by Ian Goldberg and others at the University of California Berkeley and acquired by PumaTech. Released in 2001, Mobile Explorer 3.0 added iMode compatibility plus numerous proprietary schemes. By imaginatively combining these proprietary schemes with WAP protocols, MME3.0 implemented OTA database synchronisation, push email, push information clients and PIM functionality. The cancelled Sony Ericsson CMD-Z700 was to feature heavy integration with MME3.0. Although Mobile Explorer was ahead of its time in the mobile phone space, development was stopped in 2002.
In 2002, Inc. offered Web Pro on Tungsten PDAs based upon a Novarra browser. PalmSource offered a competing Web browser based on Access Netfront. Opera Software pioneered with its Small Screen Medium Screen Rendering technology; the Opera web browser is able to reformat regular web pages for optimal fit on small screens and medium-sized screens. It was the first available mobile browser to support Ajax and the first mobile browser to pass ACID2 test. Distinct from a mobile browser is a web-based emulator, which uses a "Virtual Handset" to display WAP pages on a computer screen, implemented either in Java or as an HTML transcoder; the following are some of the more popular mobile browsers. Some mobile browsers are miniaturized web browsers, so some mobile device providers provide browsers for desktop and laptop computers. Mobile transcoders reformat and compress web content for mobile devices and must be used in conjunction with built-in or user-installed mobile browsers; the following are several leading mobile transcoding services.
Openwave Web Adapter - used by Vodacom Vision Mobile Server Skweezer - used by Orange, JumpTap, Medio and others Teashark Opera Mini Loband by Aptivate Google Mobilizer — Defunct since February 2016. Replaced with Google Web Light. Smart
Personal digital assistant
A personal digital assistant known as a handheld PC, is a variety mobile device which functions as a personal information manager. PDAs were discontinued in the early 2010s after the widespread adoption of capable smartphones, in particular those based on iOS and Android. Nearly all PDAs have the ability to connect to the Internet. A PDA has an electronic visual display. Most models have audio capabilities, allowing usage as a portable media player, enabling most of them to be used as telephones. Most PDAs can access intranets or extranets via Wi-Fi or Wireless Wide Area Networks. Sometimes, instead of buttons, PDAs employ touchscreen technology; the technology industry has recycled the term personal digital assistance. The term is more used for software that identifies a user's voice to reply to the queries; the first PDA, the Organizer, was released in 1984 by Psion, followed by Psion's Series 3, in 1991. The latter began to resemble the more familiar PDA style, including a full keyboard; the term PDA was first used on January 7, 1992 by Apple Computer CEO John Sculley at the Consumer Electronics Show in Las Vegas, referring to the Apple Newton.
In 1994, IBM introduced the first PDA with full telephone functionality, the IBM Simon, which can be considered the first smartphone. In 1996, Nokia introduced a PDA with telephone functionality, the 9000 Communicator, which became the world's best-selling PDA. Another early entrant in this market was Palm, with a line of PDA products which began in March 1996. A typical PDA has a touchscreen for navigation, a memory card slot for data storage, IrDA, Bluetooth and/or Wi-Fi. However, some PDAs may not have a touchscreen, using softkeys, a directional pad, a numeric keypad or a thumb keyboard for input. To have the functions expected of a PDA, a device's software includes an appointment calendar, a to-do list, an address book for contacts, a calculator, some sort of memo program. PDAs with wireless data connections typically include an email client and a Web browser, may or may not include telephony functionality. Many of the original PDAs, such as the Apple Newton and Palm Pilot, featured a touchscreen for user interaction, having only a few buttons—usually reserved for shortcuts to often-used programs.
Some touchscreen PDAs, including Windows Mobile devices, had a detachable stylus to facilitate making selections. The user interacts with the device by tapping the screen to select buttons or issue commands, or by dragging a finger on the screen to make selections or scroll. Typical methods of entering text on touchscreen PDAs include: A virtual keyboard, where a keyboard is shown on the touchscreen. Text is entered by tapping the on-screen keyboard with stylus. An external keyboard connected via Infrared port, or Bluetooth; some users may choose a chorded keyboard for one-handed use. Handwriting recognition, where letters or words are written on the touchscreen with a stylus, the PDA converts the input to text. Recognition and computation of handwritten horizontal and vertical formulas, such as "1 + 2 =", may be a feature. Stroke recognition allows the user to make a predefined set of strokes on the touchscreen, sometimes in a special input area, representing the various characters to be input.
The strokes are simplified character shapes, making them easier for the device to recognize. One known stroke recognition system is Palm's Graffiti. Despite research and development projects, end-users experience mixed results with handwriting recognition systems; some find it frustrating and inaccurate, while others are satisfied with the quality of the recognition. Touchscreen PDAs intended for business use, such as the BlackBerry and Palm Treo also offer full keyboards and scroll wheels or thumbwheels to facilitate data entry and navigation. Many touchscreen PDAs support some form of external keyboard as well. Specialized folding keyboards, which offer a full-sized keyboard but collapse into a compact size for transport, are available for many models. External keyboards may attach to the PDA directly, using a cable, or may use wireless technology such as infrared or Bluetooth to connect to the PDA. Newer PDAs, such as the HTC HD2, Apple iPhone, Apple iPod Touch, Palm Pre, Palm Pre Plus, Palm Pixi, Palm Pixi Plus, Google Android include more advanced forms of touchscreen that can register multiple touches simultaneously.
These "multi-touch" displays allow for more sophisticated interfaces using various gestures entered with one or more fingers. Although many early PDAs did not have memory card slots, now most have either some form of Secure Digital slot, a CompactFlash slot or a combination of the two. Although designed for memory, Secure Digital Input/Output and CompactFlash cards are available that provide accessories like Wi-Fi or digital cameras, if the device can support them; some PDAs have a USB port for USB flash drives. Some PDAs use microSD cards, which are electronically compatible with SD cards, but have a much smaller physical size. While early PDAs connected to a user's personal computer via serial ports or another proprietary connection, many today connect via a USB cable. Older PDAs were unable to connect to each other via USB, as their implementations of USB didn't support acting as the "host"; some early PDAs were able to connect to the Internet indirectly by means of an external modem connected via the PDA's serial port or "sync" connector, or directly by using an expansion card that provided an Ethernet port.
Most modern PDAs have a popular wireless protocol for mobile devices. Bluetooth can be used to connect keyboards, headsets, GPS receiver