A web browser is a software application for accessing information on the World Wide Web. Each individual web page and video is identified by a distinct Uniform Resource Locator, enabling browsers to retrieve these resources from a web server and display them on the user's device. A web browser is not the same thing as a search engine, though the two are confused. For a user, a search engine is just a website, such as google.com, that stores searchable data about other websites. But to connect to a website's server and display its web pages, a user needs to have a web browser installed on their device; the most popular browsers are Chrome, Safari, Internet Explorer, Edge. The first web browser, called WorldWideWeb, was invented in 1990 by Sir Tim Berners-Lee, he recruited Nicola Pellow to write the Line Mode Browser, which displayed web pages on dumb terminals. 1993 was a landmark year with the release of Mosaic, credited as "the world's first popular browser". Its innovative graphical interface made the World Wide Web system easy to use and thus more accessible to the average person.
This, in turn, sparked the Internet boom of the 1990s when the Web grew at a rapid rate. Marc Andreessen, the leader of the Mosaic team, soon started his own company, which released the Mosaic-influenced Netscape Navigator in 1994. Navigator became the most popular browser. Microsoft debuted Internet Explorer in 1995. Microsoft was able to gain a dominant position for two reasons: it bundled Internet Explorer with its popular Microsoft Windows operating system and did so as freeware with no restrictions on usage; the market share of Internet Explorer peaked at over 95% in 2002. In 1998, desperate to remain competitive, Netscape launched what would become the Mozilla Foundation to create a new browser using the open source software model; this work evolved into Firefox, first released by Mozilla in 2004. Firefox reached a 28% market share in 2011. Apple released its Safari browser in 2003, it remains the dominant browser on Apple platforms. The last major entrant to the browser market was Google, its Chrome browser, which debuted in 2008, has been a huge success.
Once a web page has been retrieved, the browser's rendering engine displays it on the user's device. This includes video formats supported by the browser. Web pages contain hyperlinks to other pages and resources; each link contains a URL, when it is clicked, the browser navigates to the new resource. Thus the process of bringing content to the user begins again. To implement all of this, modern browsers are a combination of numerous software components. Web browsers can be configured with a built-in menu. Depending on the browser, the menu may be named Options, or Preferences; the menu has different types of settings. For example, users can change their home default search engine, they can change default web page colors and fonts. Various network connectivity and privacy settings are usually available. During the course of browsing, cookies received from various websites are stored by the browser; some of them contain login credentials or site preferences. However, others are used for tracking user behavior over long periods of time, so browsers provide settings for removing cookies when exiting the browser.
Finer-grained management of cookies requires a browser extension. The most popular browsers have a number of features in common, they allow users to browse in a private mode. They can be customized with extensions, some of them provide a sync service. Most browsers have these user interface features: Allow the user to open multiple pages at the same time, either in different browser windows or in different tabs of the same window. Back and forward buttons to go back to the previous page forward to the next one. A refresh or reload button to reload the current page. A stop button to cancel loading the page. A home button to return to the user's home page. An address bar to display it. A search bar to input terms into a search engine. There are niche browsers with distinct features. One example is text-only browsers that can benefit people with slow Internet connections or those with visual impairments. Mobile browser List of web browsers Comparison of web browsers Media related to Web browsers at Wikimedia Commons
The Internet is the global system of interconnected computer networks that use the Internet protocol suite to link devices worldwide. It is a network of networks that consists of private, academic and government networks of local to global scope, linked by a broad array of electronic and optical networking technologies; the Internet carries a vast range of information resources and services, such as the inter-linked hypertext documents and applications of the World Wide Web, electronic mail and file sharing. Some publications no longer capitalize "internet"; the origins of the Internet date back to research commissioned by the federal government of the United States in the 1960s to build robust, fault-tolerant communication with computer networks. The primary precursor network, the ARPANET served as a backbone for interconnection of regional academic and military networks in the 1980s; the funding of the National Science Foundation Network as a new backbone in the 1980s, as well as private funding for other commercial extensions, led to worldwide participation in the development of new networking technologies, the merger of many networks.
The linking of commercial networks and enterprises by the early 1990s marked the beginning of the transition to the modern Internet, generated a sustained exponential growth as generations of institutional and mobile computers were connected to the network. Although the Internet was used by academia since the 1980s, commercialization incorporated its services and technologies into every aspect of modern life. Most traditional communication media, including telephony, television, paper mail and newspapers are reshaped, redefined, or bypassed by the Internet, giving birth to new services such as email, Internet telephony, Internet television, online music, digital newspapers, video streaming websites. Newspaper and other print publishing are adapting to website technology, or are reshaped into blogging, web feeds and online news aggregators; the Internet has enabled and accelerated new forms of personal interactions through instant messaging, Internet forums, social networking. Online shopping has grown exponentially both for major retailers and small businesses and entrepreneurs, as it enables firms to extend their "brick and mortar" presence to serve a larger market or sell goods and services online.
Business-to-business and financial services on the Internet affect supply chains across entire industries. The Internet has no single centralized governance in either technological implementation or policies for access and usage; the overreaching definitions of the two principal name spaces in the Internet, the Internet Protocol address space and the Domain Name System, are directed by a maintainer organization, the Internet Corporation for Assigned Names and Numbers. The technical underpinning and standardization of the core protocols is an activity of the Internet Engineering Task Force, a non-profit organization of loosely affiliated international participants that anyone may associate with by contributing technical expertise. In November 2006, the Internet was included on USA Today's list of New Seven Wonders; when the term Internet is used to refer to the specific global system of interconnected Internet Protocol networks, the word is a proper noun that should be written with an initial capital letter.
In common use and the media, it is erroneously not capitalized, viz. the internet. Some guides specify that the word should be capitalized when used as a noun, but not capitalized when used as an adjective; the Internet is often referred to as the Net, as a short form of network. As early as 1849, the word internetted was used uncapitalized as an adjective, meaning interconnected or interwoven; the designers of early computer networks used internet both as a noun and as a verb in shorthand form of internetwork or internetworking, meaning interconnecting computer networks. The terms Internet and World Wide Web are used interchangeably in everyday speech. However, the World Wide Web or the Web is only one of a large number of Internet services; the Web is a collection of interconnected documents and other web resources, linked by hyperlinks and URLs. As another point of comparison, Hypertext Transfer Protocol, or HTTP, is the language used on the Web for information transfer, yet it is just one of many languages or protocols that can be used for communication on the Internet.
The term Interweb is a portmanteau of Internet and World Wide Web used sarcastically to parody a technically unsavvy user. Research into packet switching, one of the fundamental Internet technologies, started in the early 1960s in the work of Paul Baran and Donald Davies. Packet-switched networks such as the NPL network, ARPANET, the Merit Network, CYCLADES, Telenet were developed in the late 1960s and early 1970s; the ARPANET project led to the development of protocols for internetworking, by which multiple separate networks could be joined into a network of networks. ARPANET development began with two network nodes which were interconnected between the Network Measurement Center at the University of California, Los Angeles Henry Samueli School of Engineering and Applied Science directed by Leonard Kleinrock, the NLS system at SRI International by Douglas Engelbart in Menlo Park, California, on 29 October 1969; the third site was the Culler-Fried Interactive Mathematics Center at the University of California, Santa Barbara, followed by the University of
Fast flux is a DNS technique used by botnets to hide phishing and malware delivery sites behind an ever-changing network of compromised hosts acting as proxies. It can refer to the combination of peer-to-peer networking, distributed command and control, web-based load balancing and proxy redirection used to make malware networks more resistant to discovery and counter-measures; the Storm Worm is one of the first malware variants to make use of this technique. The basic idea behind Fast flux is to have numerous IP addresses associated with a single qualified domain name, where the IP addresses are swapped in and out with high frequency, through changing DNS records. Internet users may see fast flux used in phishing attacks linked to criminal organizations, including attacks on social network services. While security researchers have been aware of the technique since at least November 2006, the technique only received wider attention in the security trade press starting from July 2007; the simplest type of fast flux, named "single-flux", is characterized by multiple individual nodes within the network registering and de-registering their addresses as part of the DNS A record list for a single DNS name.
This combines round robin DNS with short—usually less than five minutes -- TTL values to create a changing list of destination addresses for that single DNS name. The list can be thousands of entries long. A more sophisticated type of fast flux, referred to itself as "double-flux", is characterized by multiple nodes within the network registering and de-registering their addresses as part of the DNS Name Server record list for the DNS zone; this provides an additional layer of survivability within the malware network. Within a malware attack, the DNS records will point to a compromised system that will act as a proxy server; this method prevents some of the traditionally best defense mechanisms from working — e.g. IP-based access control lists; the method can mask the systems of attackers, which will exploit the network through a series of proxies and make it much more difficult to identify the attackers' network. The record will point to an IP where bots go for registration, to receive instructions, or to activate attacks.
Because the IPs are proxified, it is possible to disguise the originating source of these instructions, increasing the survival rate as IP-based block lists are put in place. The most effective measure against fast flux is to take down the domain name. Registrars are, reluctant to do so because domain owners are legitimate customers for them and there's no worldwide-enforced policy of what constitutes an abuse. In addition to this, including fast flux operators, are their main source of income. Security experts keep working on measures to ease this process. Other measures can be taken by local network administrators. A network admin can force endpoints within their network to only be able to use local DNS servers by blocking all egress DNS traffic, blackhole requests for malicious domains at the DNS level. Alternatively, administrators with network devices capable of doing layer 7 inspection and intervention can set up policies that reset connections that attempt to resolve or make HTTP requests involving malicious domains.
Avalanche - implemented double fast flux on 800,000 domains Domain generation algorithm - A malware control technique where multiple domain names are generated by victim hosts. Spamhaus explanation of Fast Flux hosting Phishing by proxy SANS Internet Storm Center diary from 2006-11-28 describes use of compromised hosts within botnets making use of fast flux techniques to deliver malware. MySpace Phish and Drive-by attack vector propagating Fast Flux network growth SANS Internet Storm Center diary from 2007-06-26 with technical details on FluxBot and fast flux techniques. Know Your Enemy: Fast-Flux Service Networks. Measuring and Detecting Fast-Flux Service Networks article by Holz et al. from February 2008 with empirical measurement results on fast flux. Fast flux foils bot-net takedown SecurityFocus article from 2007-07-09 describing impact of fast flux on botnet counter-measures. Attackers Hide in Fast Flux darkreading article from 2007-07-17 on the use of fast flux by criminal organizations behind malware.
CRYPTO-GRAM October 15, 2007 issue Bruce Schneier mentions fast flux as a DNS technique utilized by the Storm Worm. ATLAS Summary Report - Real-time global report of fast flux activity. SAC 025 SSAC Advisory on Fast Flux Hosting and DNS GNSO Issues Report on Fast Flux Hosting FluXOR project from Computer and Network Security Lab @ Università degli Studi di Milano
A domain name is a label that identifies a network domain: a distinct group of computers under a central administration or authority. Within the Internet, domain names are formed by the procedures of the Domain Name System. Any name registered in the DNS is a domain name. Domain names are used in various networking contexts and for application-specific naming and addressing purposes. In general, a domain name represents an Internet Protocol resource, such as a personal computer used to access the Internet, a server computer hosting a web site, or the web site itself or any other service communicated via the Internet. In 2017, 330.6 million domain names had been registered. Domain names are organized in subordinate levels of the DNS root domain, nameless; the first-level set of domain names are the top-level domains, including the generic top-level domains, such as the prominent domains com, net and org, the country code top-level domains. Below these top-level domains in the DNS hierarchy are the second-level and third-level domain names that are open for reservation by end-users who wish to connect local area networks to the Internet, create other publicly accessible Internet resources or run web sites.
The registration of these domain names is administered by domain name registrars who sell their services to the public. A qualified domain name is a domain name, specified with all labels in the hierarchy of the DNS, having no parts omitted. Labels in the Domain Name System are case-insensitive, may therefore be written in any desired capitalization method, but most domain names are written in lowercase in technical contexts. Domain names serve to identify Internet resources, such as computers and services, with a text-based label, easier to memorize than the numerical addresses used in the Internet protocols. A domain name may represent entire collections of individual instances. Individual Internet host computers use domain names as host identifiers called host names; the term host name is used for the leaf labels in the domain name system without further subordinate domain name space. Host names appear as a component in Uniform Resource Locators for Internet resources such as web sites. Domain names are used as simple identification labels to indicate ownership or control of a resource.
Such examples are the realm identifiers used in the Session Initiation Protocol, the Domain Keys used to verify DNS domains in e-mail systems, in many other Uniform Resource Identifiers. An important function of domain names is to provide recognizable and memorizable names to numerically addressed Internet resources; this abstraction allows any resource to be moved to a different physical location in the address topology of the network, globally or locally in an intranet. Such a move requires changing the IP address of a resource and the corresponding translation of this IP address to and from its domain name. Domain names are used to establish a unique identity. Organizations can choose a domain name that corresponds to their name, helping Internet users to reach them easily. A generic domain is a name that defines a general category, rather than a specific or personal instance, for example, the name of an industry, rather than a company name; some examples of generic names are books.com, music.com, travel.info.
Companies have created brands based on generic names, such generic domain names may be valuable Domain names are simply referred to as domains and domain name registrants are referred to as domain owners, although domain name registration with a registrar does not confer any legal ownership of the domain name, only an exclusive right of use for a particular duration of time. The use of domain names in commerce may subject them to trademark law; the practice of using a simple memorable abstraction of a host's numerical address on a computer network dates back to the ARPANET era, before the advent of today's commercial Internet. In the early network, each computer on the network retrieved the hosts file from a computer at SRI, which mapped computer host names to numerical addresses; the rapid growth of the network made it impossible to maintain a centrally organized hostname registry and in 1983 the Domain Name System was introduced on the ARPANET and published by the Internet Engineering Task Force as RFC 882 and RFC 883.
Today, the Internet Corporation for Assigned Names and Numbers manages the top-level development and architecture of the Internet domain name space. It authorizes domain name registrars, through which domain names may be reassigned; the domain name space consists of a tree of domain names. Each node in the tree holds information associated with the domain name; the tree sub-divides into zones beginning at the DNS root zone. A domain name consists of one or more parts, technically called labels, that are conventionally concatenated, delimited by dots, such as example.com. The right-most label conveys the top-level domain; the hierarchy of domains descends from the right to the left label in the name. For example: the label example specifies a node example.com as a subdomain of the com domain, www is a label to create www.example.com, a subdomain of example.com. Each label may contain from 1 to 63 octets; the empty label is reserved for the root node and when qualified is expressed as the empty label terminated by a dot.
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A website or Web site is a collection of related network web resources, such as web pages, multimedia content, which are identified with a common domain name, published on at least one web server. Notable examples are wikipedia.org, google.com, amazon.com. Websites can be accessed via a public Internet Protocol network, such as the Internet, or a private local area network, by a uniform resource locator that identifies the site. Websites can be used in various fashions. Websites are dedicated to a particular topic or purpose, ranging from entertainment and social networking to providing news and education. All publicly accessible websites collectively constitute the World Wide Web, while private websites, such as a company's website for its employees, are part of an intranet. Web pages, which are the building blocks of websites, are documents composed in plain text interspersed with formatting instructions of Hypertext Markup Language, they may incorporate elements from other websites with suitable markup anchors.
Web pages are accessed and transported with the Hypertext Transfer Protocol, which may optionally employ encryption to provide security and privacy for the user. The user's application a web browser, renders the page content according to its HTML markup instructions onto a display terminal. Hyperlinking between web pages conveys to the reader the site structure and guides the navigation of the site, which starts with a home page containing a directory of the site web content; some websites require user subscription to access content. Examples of subscription websites include many business sites, news websites, academic journal websites, gaming websites, file-sharing websites, message boards, web-based email, social networking websites, websites providing real-time stock market data, as well as sites providing various other services. End users can access websites on a range of devices, including desktop and laptop computers, tablet computers and smart TVs; the World Wide Web was created in 1990 by the British CERN physicist Tim Berners-Lee.
On 30 April 1993, CERN announced. Before the introduction of HTML and HTTP, other protocols such as File Transfer Protocol and the gopher protocol were used to retrieve individual files from a server; these protocols offer a simple directory structure which the user navigates and where they choose files to download. Documents were most presented as plain text files without formatting, or were encoded in word processor formats. Websites can be used in various fashions. Websites can be the work of an individual, a business or other organization, are dedicated to a particular topic or purpose. Any website can contain a hyperlink to any other website, so the distinction between individual sites, as perceived by the user, can be blurred. Websites are written in, or converted to, HTML and are accessed using a software interface classified as a user agent. Web pages can be viewed or otherwise accessed from a range of computer-based and Internet-enabled devices of various sizes, including desktop computers, tablet computers and smartphones.
A website is hosted on a computer system known as a web server called an HTTP server. These terms can refer to the software that runs on these systems which retrieves and delivers the web pages in response to requests from the website's users. Apache is the most used web server software and Microsoft's IIS is commonly used; some alternatives, such as Nginx, Hiawatha or Cherokee, are functional and lightweight. A static website is one that has web pages stored on the server in the format, sent to a client web browser, it is coded in Hypertext Markup Language. Images are used to effect the desired appearance and as part of the main content. Audio or video might be considered "static" content if it plays automatically or is non-interactive; this type of website displays the same information to all visitors. Similar to handing out a printed brochure to customers or clients, a static website will provide consistent, standard information for an extended period of time. Although the website owner may make updates periodically, it is a manual process to edit the text and other content and may require basic website design skills and software.
Simple forms or marketing examples of websites, such as classic website, a five-page website or a brochure website are static websites, because they present pre-defined, static information to the user. This may include information about a company and its products and services through text, animations, audio/video, navigation menus. Static websites can be edited using four broad categories of software: Text editors, such as Notepad or TextEdit, where content and HTML markup are manipulated directly within the editor program WYSIWYG offline editors, such as Microsoft FrontPage and Adobe Dreamweaver, with which the site is edited using a GUI and the final HTML markup is generated automatically by the editor software WYSIWYG online editors which create media rich online presentation like web pages, intro, blogs, an
Electronic mail is a method of exchanging messages between people using electronic devices. Invented by Ray Tomlinson, email first entered limited use in the 1960s and by the mid-1970s had taken the form now recognized as email. Email operates across computer networks, which today is the Internet; some early email systems required the author and the recipient to both be online at the same time, in common with instant messaging. Today's email systems are based on a store-and-forward model. Email servers accept, forward and store messages. Neither the users nor their computers are required to be online simultaneously. An ASCII text-only communications medium, Internet email was extended by Multipurpose Internet Mail Extensions to carry text in other character sets and multimedia content attachments. International email, with internationalized email addresses using UTF-8, has been standardized, but as of 2017 it has not been adopted; the history of modern Internet email services reaches back to the early ARPANET, with standards for encoding email messages published as early as 1973.
An email message sent in the early 1970s looks similar to a basic email sent today. Email had an important role in creating the Internet, the conversion from ARPANET to the Internet in the early 1980s produced the core of the current services; the term electronic mail was used generically for any electronic document transmission. For example, several writers in the early 1970s used the term to describe fax document transmission; as a result, it is difficult to find the first citation for the use of the term with the more specific meaning it has today. Electronic mail has been most called email or e-mail since around 1993, but variations of the spelling have been used: email is the most common form used online, is required by IETF Requests for Comments and working groups and by style guides; this spelling appears in most dictionaries. E-mail is the format that sometimes appears in edited, published American English and British English writing as reflected in the Corpus of Contemporary American English data, but is falling out of favor in some style guides.
Mail was the form used in the original protocol standard, RFC 524. The service is referred to as mail, a single piece of electronic mail is called a message. EMail is a traditional form, used in RFCs for the "Author's Address" and is expressly required "for historical reasons". E-mail is sometimes used, capitalizing the initial E as in similar abbreviations like E-piano, E-guitar, A-bomb, H-bomb. An Internet e-mail consists of an content. Computer-based mail and messaging became possible with the advent of time-sharing computers in the early 1960s, informal methods of using shared files to pass messages were soon expanded into the first mail systems. Most developers of early mainframes and minicomputers developed similar, but incompatible, mail applications. Over time, a complex web of gateways and routing systems linked many of them. Many US universities were part of the ARPANET, which aimed at software portability between its systems; that portability helped make the Simple Mail Transfer Protocol influential.
For a time in the late 1980s and early 1990s, it seemed that either a proprietary commercial system or the X.400 email system, part of the Government Open Systems Interconnection Profile, would predominate. However, once the final restrictions on carrying commercial traffic over the Internet ended in 1995, a combination of factors made the current Internet suite of SMTP, POP3 and IMAP email protocols the standard; the diagram to the right shows a typical sequence of events that takes place when sender Alice transmits a message using a mail user agent addressed to the email address of the recipient. The MUA formats the message in email format and uses the submission protocol, a profile of the Simple Mail Transfer Protocol, to send the message content to the local mail submission agent, in this case smtp.a.org. The MSA determines the destination address provided in the SMTP protocol, in this case firstname.lastname@example.org, a qualified domain address. The part before the @ sign is the local part of the address the username of the recipient, the part after the @ sign is a domain name.
The MSA resolves a domain name to determine the qualified domain name of the mail server in the Domain Name System. The DNS server for the domain b.org responds with any MX records listing the mail exchange servers for that domain, in this case mx.b.org, a message transfer agent server run by the recipient's ISP. smtp.a.org sends the message to mx.b.org using SMTP. This server may need to forward the message to other MTAs before the message reaches the final message delivery agent; the MDA delivers it to the mailbox of user bob. Bob's MUA picks up the message using either the Post Office Protocol or the Internet Message Access Protocol. In addition to this example and complications exist in the email system: Alice or Bob may use a client connected to a corporate email system, such as IBM Lotus Notes or Microsoft Exchange; these systems have their own internal email format and their clients communicate with the email server using a vendor-specific, proprietary protocol. The server sends or receives email via the Internet through the product's Internet mail gateway which does any necessary reformatt