Cascading Style Sheets
This cascading priority scheme is predictable. The CSS specifications are maintained by the World Wide Web Consortium. Internet media type text/css is registered for use with CSS by RFC 2318; the W3C operates a free CSS validation service for CSS documents. In addition to HTML, other markup languages support the use of CSS including XHTML, plain XML, SVG, XUL. CSS has a simple syntax and uses a number of English keywords to specify the names of various style properties. A style sheet consists of a list of rules; each rule or rule-set consists of one or more selectors, a declaration block. In CSS, selectors declare which part of the markup a style applies to by matching tags and attributes in the markup itself. Selectors may apply to the following: all elements of a specific type, e.g. the second-level headers h2 elements specified by attribute, in particular: id: an identifier unique within the document class: an identifier that can annotate multiple elements in a document elements depending on how they are placed relative to others in the document tree.
Classes and IDs are case-sensitive, start with letters, can include alphanumeric characters and underscores. A class may apply to any number of instances of any elements. An ID may only be applied to a single element. Pseudo-classes are used in CSS selectors to permit formatting based on information, not contained in the document tree. One example of a used pseudo-class is:hover, which identifies content only when the user “points to” the visible element by holding the mouse cursor over it, it is #elementid: hover. A pseudo-class classifies document elements, such as:link or:visited, whereas a pseudo-element makes a selection that may consist of partial elements, such as::first-line or::first-letter. Selectors may be combined in many ways to achieve great flexibility. Multiple selectors may be joined in a spaced list to specify elements by location, element type, id, class, or any combination thereof; the order of the selectors is important. For example, div.myClass applies to all elements of class myClass that are inside div elements, whereas.myClass div applies to all div elements that are in elements of class myClass.
The following table provides a summary of selector syntax indicating usage and the version of CSS that introduced it. A declaration block consists of a list of declarations in braces; each declaration itself consists of a property, a colon, a value. If there are multiple declarations in a block, a semi-colon must be inserted to separate each declaration. Properties are specified in the CSS standard; each property has a set of possible values. Some properties can affect any type of element, others apply only to particular groups of elements. Values may be keywords, such as "center" or "inherit", or numerical values, such as 200px, 50vw or 80%. Color values can be specified with keywords, hexadecimal values, RGB values on a 0 to 255 scale, RGBA values that specify both color and alpha transparency, or HSL or HSLA values. Before CSS, nearly all presentational attributes of HTML documents were contained within the HTML markup. All font colors, background styles, element alignments and sizes had to be explicitly described repeatedly, within the HTML.
CSS lets authors move much of that information to another file, the style sheet, resulting in simpler HTML. For example, sub-headings, sub-sub-headings, etc. are defined structurally using HTML. In print and on the screen, choice of font, size and emphasis for these elements is presentational. Before CSS, document authors who wanted to assign such typographic characteristics to, all h2 headings had to repeat HTML presentational markup for each occurrence of that heading type; this made documents more complex and more error-prone and difficult to maintain. CSS allows the separation of presentation from structure. CSS can define color, text alignment, borders, spacing and many other typographic characteristics, can do so independently for on-screen and printed views. CSS defines non-visual styles, such as reading speed and emphasis for aural text readers; the W3C has now deprecated the use of all presentational HTML markup. For example, under pre-CSS HTML, a heading element defined with red text would be written as: Using CSS, the sam
It describes 18 elements comprising the initial simple design of HTML. Except for the hyperlink tag, these were influenced by SGMLguid, an in-house Standard Generalized Markup Language -based documentation format at CERN. Eleven of these elements still exist in HTML 4. HTML is a markup language that web browsers use to interpret and compose text and other material into visual or audible web pages. Default characteristics for every item of HTML markup are defined in the browser, these characteristics can be altered or enhanced by the web page designer's additional use of CSS. Many of the text elements are found in the 1988 ISO technical report TR 9537 Techniques for using SGML, which in turn covers the features of early text formatting languages such as that used by the RUNOFF command developed in the early 1960s for the CTSS operating system: these formatting commands were derived from the commands used by typesetters to manually format documents. However, the SGML concept of generalized markup is based on elements rather than print effects, with the separation of structure and markup.
Berners-Lee considered HTML to be an application of SGML. It was formally defined as such by the Internet Engineering Task Force with the mid-1993 publication of the first proposal for an HTML specification, the "Hypertext Markup Language" Internet Draft by Berners-Lee and Dan Connolly, which included an SGML Document type definition to define the grammar; the draft expired after six months, but was notable for its acknowledgment of the NCSA Mosaic browser's custom tag for embedding in-line images, reflecting the IETF's philosophy of basing standards on successful prototypes. Dave Raggett's competing Internet-Draft, "HTML+", from late 1993, suggested standardizing already-implemented features like tables and fill-out forms. After the HTML and HTML+ drafts expired in early 1994, the IETF created an HTML Working Group, which in 1995 completed "HTML 2.0", the first HTML specification intended to be treated as a standard against which future implementations should be based. Further development under the auspices of the IETF was stalled by competing interests.
Since 1996, the HTML specifications have been maintained, with input from commercial software vendors, by the World Wide Web Consortium. However, in 2000, HTML became an international standard. HTML 4.01 was published in late 1999, with further errata published through 2001. In 2004, development began on HTML5 in the Web Hypertext Application Technology Working Group, which became a joint deliverable with the W3C in 2008, completed and standardized on 28 October 2014. November 24, 1995 HTML 2.0 was published as RFC 1866. Supplemental RFCs added capabilities: November 25, 1995: RFC 1867 May 1996: RFC 1942 August 1996: RFC 1980 January 1997: RFC 2070 January 14, 1997 HTML 3.2 was published as a W3C Recommendation. It was the first version developed and standardized by the W3C, as the IETF had closed its HTML Working Group on September 12, 1996. Code-named "Wilbur", HTML 3.2 dropped math formulas reconciled overlap among various proprietary extensions and adopted most of Netscape's visual markup tags.
Netscape's blink element and Microsoft's marquee element were omitted due to a mutual agreement between the two companies. A markup for mathematical formu
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
World Wide Web
The World Wide Web known as the Web, is an information space where documents and other web resources are identified by Uniform Resource Locators, which may be interlinked by hypertext, are accessible over the Internet. The resources of the WWW may be accessed by users by a software application called a web browser. English scientist Tim Berners-Lee invented the World Wide Web in 1989, he wrote the first web browser in 1990 while employed at CERN near Switzerland. The browser was released outside CERN in 1991, first to other research institutions starting in January 1991 and to the general public in August 1991; the World Wide Web has been central to the development of the Information Age and is the primary tool billions of people use to interact on the Internet. Web resources may be any type of downloaded media, but web pages are hypertext media that have been formatted in Hypertext Markup Language; such formatting allows for embedded hyperlinks that contain URLs and permit users to navigate to other web resources.
In addition to text, web pages may contain images, video and software components that are rendered in the user's web browser as coherent pages of multimedia content. Multiple web resources with a common theme, a common domain name, or both, make up a website. Websites are stored in computers that are running a program called a web server that responds to requests made over the Internet from web browsers running on a user's computer. Website content can be provided by a publisher, or interactively where users contribute content or the content depends upon the users or their actions. Websites may be provided for a myriad of informative, commercial, governmental, or non-governmental reasons. Tim Berners-Lee's vision of a global hyperlinked information system became a possibility by the second half of the 1980s. By 1985, the global Internet began to proliferate in Europe and the Domain Name System came into being. In 1988 the first direct IP connection between Europe and North America was made and Berners-Lee began to discuss the possibility of a web-like system at CERN.
While working at CERN, Berners-Lee became frustrated with the inefficiencies and difficulties posed by finding information stored on different computers. On March 12, 1989, he submitted a memorandum, titled "Information Management: A Proposal", to the management at CERN for a system called "Mesh" that referenced ENQUIRE, a database and software project he had built in 1980, which used the term "web" and described a more elaborate information management system based on links embedded as text: "Imagine the references in this document all being associated with the network address of the thing to which they referred, so that while reading this document, you could skip to them with a click of the mouse." Such a system, he explained, could be referred to using one of the existing meanings of the word hypertext, a term that he says was coined in the 1950s. There is no reason, the proposal continues, why such hypertext links could not encompass multimedia documents including graphics and video, so that Berners-Lee goes on to use the term hypermedia.
With help from his colleague and fellow hypertext enthusiast Robert Cailliau he published a more formal proposal on 12 November 1990 to build a "Hypertext project" called "WorldWideWeb" as a "web" of "hypertext documents" to be viewed by "browsers" using a client–server architecture. At this point HTML and HTTP had been in development for about two months and the first Web server was about a month from completing its first successful test; this proposal estimated that a read-only web would be developed within three months and that it would take six months to achieve "the creation of new links and new material by readers, authorship becomes universal" as well as "the automatic notification of a reader when new material of interest to him/her has become available". While the read-only goal was met, accessible authorship of web content took longer to mature, with the wiki concept, WebDAV, Web 2.0 and RSS/Atom. The proposal was modelled after the SGML reader Dynatext by Electronic Book Technology, a spin-off from the Institute for Research in Information and Scholarship at Brown University.
The Dynatext system, licensed by CERN, was a key player in the extension of SGML ISO 8879:1986 to Hypermedia within HyTime, but it was considered too expensive and had an inappropriate licensing policy for use in the general high energy physics community, namely a fee for each document and each document alteration. A NeXT Computer was used by Berners-Lee as the world's first web server and to write the first web browser, WorldWideWeb, in 1990. By Christmas 1990, Berners-Lee had built all the tools necessary for a working Web: the first web browser and the first web server; the first web site, which described the project itself, was published on 20 December 1990. The first web page may be lost, but Paul Jones of UNC-Chapel Hill in North Carolina announced in May 2013 that Berners-Lee gave him what he says is the oldest known web page during a 1991 visit to UNC. Jones stored it on his NeXT computer. On 6 August 1991, Berners-Lee published a short summary of the World Wide Web project on the newsgroup alt.hypertext.
This date is sometimes confused with the public availability of the first web servers, which had occurred months earlier. As another example of such confusion, several news media reported that the first photo on the Web was published by Berners-Lee in 1992, an image of the CERN house band Les Horribles Cernettes taken by Silvano de Gennaro.
NTT DoCoMo's i-mode is a mobile internet service popular in Japan. Unlike Wireless Application Protocol, i-mode encompasses a wider variety of internet standards, including web access, e-mail, the packet-switched network that delivers the data. I-mode users have access to various services such as e-mail, sports results, weather forecast, financial services, ticket booking. Content is provided by specialized services from the mobile carrier, which allows them to have tighter control over billing. Like WAP, i-mode delivers only those services that are converted for the service, or are converted through gateways. In contrast with the Wireless Application Protocol standard, which used Wireless Markup Language on top of a protocol stack for wireless handheld devices, i-mode borrows from DoCoMo proprietary protocols ALP and TLP, as well as fixed Internet data formats such as C-HTML, a subset of the HTML language designed by DoCoMo. C-HTML was designed for small devices with hardware restrictions such as such lower memory, low-power CPUs with limited or no storage capabilities, small monochrome display screens, single-character fonts and limited input methods.
As a simpler form of HTML, C-HTML does not support tables, image maps, multiple fonts and styling of fonts, background colors and images, frames, or style sheets, is limited to a monochromatic display.i-mode phones have a special i-mode button for the user to access the start menu. There are more than 12,000 official sites and around 100,000 or more unofficial i-mode sites, which are not linked to DoCoMo's i-mode portal page and DoCoMo's billing services. NTT DoCoMo supervises the content and operations of all official i-mode sites, most of which are commercial; these official sites are accessed through DoCoMo's i-mode menu but in many cases official sites can be accessed from mobile phones by typing the URL or through the use of QR code. An i-mode user pays for both received data. There are services to avoid unsolicited e-mails; the basic monthly charge is on the order of JPY ¥200 - ¥300 for i-mode not including the data transfer charges, with additional charges on a monthly subscription basis for premium services.
A variety of discount plans exist, for example family discount and flat packet plans for unlimited transfer of data at a fixed monthly charge. I-mode was launched in Japan on 22 February 1999; the content planning and service design team was led by Mari Matsunaga, while Takeshi Natsuno was responsible for the business development. Top executive Keiichi Enoki oversaw the overall development. A few months after DoCoMo launched i-mode in February 1999, DoCoMo's competitors launched similar mobile data services: KDDI launched EZweb, J-Phone launched J-Sky. Vodafone acquired J-Phone including J-Sky, renaming the service Vodafone live!, although this was different from Vodafone live! in Europe and other markets. In addition, Vodafone KK was acquired by SoftBank, an operator of Yahoo! Japan changed the name to SoftBank Mobile; as of June 2006, the mobile data services I-Mode, EZweb, J-Sky, had over 80 million subscribers in Japan. Since 2003, i-mode center is called CiRCUS, which consists of 400 NEC NX7000 HP-UX servers and occupies 4,600 m² floor space in DoCoMo's Kawasaki office.
The operation support system is called CARNiVAL, hosted in the Sanno Park Tower. I-mode usage in Japan peaked around 2008; as of 2016, it is still available, but has been eclipsed by the internet features in 3G, 4G, WiFi enabled smartphones. Seeing the tremendous success of i-mode in Japan, many operators in Europe and Australia sought to license the service through partnership with DoCoMo. Takeshi Natsuno was behind the expansion of i-mode to 17 countries worldwide. Kamel Maamria, a partner with the Boston Consulting Group and, supporting Mr. Natsuno is thought to have had a major role in the expansion of the first Japanese service outside Japan. I-mode showed fast take-up in the various countries where it was launched which led to more operators seeking to launch i-mode in their markets with the footprint reaching a total of 17 markets worldwide. While the i-mode service was an exceptional service which positioned DoCoMo as the global leader in value add services, another key success factor for i-mode was the Japanese smartphone makers who developed state of the art handsets to support i-mode.
As i-mode was exported to the rest of the world and other major handset vendors who controlled the markets at the time, refused at first to support i-mode by developing handsets which support the i-mode service. The operators who decided to launch i-mode had to rely on Japanese vendors who had no experience in international markets; as i-mode showed success in these markets, some vendors started customizing some of their handsets to support i-mode, the support was only partial and came late in time. While the service was successful during the first years after launch, the lack of adequate handsets and the emergence of new handsets from new vendors which supported new Internet services on one hand, a change of leadership of i-mode in Docomo, lead to a number of operators to migrate or integrate i-mode into new mobile Internet services; these efforts were unsuccessful, i-mode never became popular outside of Japan.i-mode was launched in the following countries: Australia, Belgium Bulgaria France Germany Greece Hong Kong Israel Ireland Italy Netherlands Russia Romania Singapore Spain
The WYSIWYG view is achieved by embedding a layout engine. This may be custom-written or based upon one used in a web browser; the goal is that, at all times during editing, the rendered result should represent what will be seen in a typical web browser. WYSIWYM is an alternative paradigm to WYSIWYG editors. Instead of focusing on the format or presentation of the document, it preserves the intended meaning of each element. For example, page headers, paragraphs, etc. are labeled as such in the editing program, displayed appropriately in the browser. A given HTML document will have an inconsistent appearance on various platforms and computers for several reasons: Different browsers and applications will render the same markup differently; the same page may display differently in Internet Explorer and Firefox on a high-resolution screen, but it will look different in the valid text-only Lynx browser. It needs to be rendered differently again on a PDA, an internet-enabled television and on a mobile phone.
Usability in a speech or braille browser, or via a screen-reader working with a conventional browser, will place demands on different aspects of the underlying HTML. All an author can do. Web browsers, like all computer software, have bugs, it is hopeless to try to design Web pages around all of the common browsers' current bugs: each time a new version of each browser comes out, a significant proportion of the World Wide Web would need re-coding to suit the new bugs and the new fixes. It is considered much wiser to design to standards, staying away from'bleeding edge' features until they settle down, wait for the browser developers to catch up to your pages, rather than the other way round. For instance, no one can argue that CSS is still'cutting edge' as there is now widespread support available in common browsers for all the major features if many WYSIWYG and other editors have not yet caught up. A single visual style can represent multiple semantic meanings Semantic meaning, derived from the underlying structure of the HTML document, is important for search engines and for various accessibility tools.
On paper we can tell from context and experience whether bold text represents a title, or emphasis, or something else. But it is difficult to convey this distinction in a WYSIWYG editor. Making a piece of text bold in a WYSIWYG editor is not sufficient to tell the reader *why* the text is bold - what the boldness represents semantically. Modern web sites are constructed in a way that makes WYSIWYG useful Modern web sites use a Content Management System or some other template processor-based means of constructing pages on the fly using content stored in a database. Individual pages are never stored in a filesystem as they may be designed and edited in a WYSIWYG editor, thus some form of abstracted template-based layout is inevitable, invalidating one of the main benefits of using a WYSIWYG editor. HTML is a structured markup language. There are certain rules on how HTML must be written if it is to conform to W3C standards for the World Wide Web. Following these rules means that web sites are accessible on all types and makes of computer, to able-bodied and people with disabilities, and