W3C is the abbreviation of World Wide Web Consortium, which means W3C Council or World Wide Web Consortium in Chinese.
Main specifications issued by W3C
So far, W3C has formulated more than 50 specifications (drafts). These specifications (drafts) include HTML, HTTP, URIs, XML, etc., as well as RDF and OWL oriented to the semantic web.
* HTML/XHTML: HTML is one of the foundations of the Web. Based on HTML, rich and colorful pages, including all kinds of information, began to appear on web pages. The HTML-based Web has stepped out of the ivory tower in a simple and easy-to-use way and become a public resource and wealth of the whole society. W3C has released several HTML versions, namely the first version of 1997, the update of 1998, and the release of HTML 4.0 1 in 1999. XHTML is an extension of HTML 4.0 1, in which the semantic functions of XML can be used. XHTML 1.0 was published as a recommended standard in June 2000. XHTML Basic is a device-independent extension of XHTML 1.0, which was released in February 2000. Subsequently, a modular version of XHTML-XHTML 1. 1 was launched in May of 20001.
* CSS:CSS is responsible for providing rich style space for web designers to design web pages. The separation mechanism of web page structure, content and expression provided by CSS greatly simplifies the management of website and improves the efficiency of website development. CSS can be used to control the presentation of any HTML and XML content. CSS 1.0 was launched in199665438+February, and CSS2.0 was released in1998 May.
XML: 65438+XML 1.0 released in February, 1998 is one of the most forward-looking and influential standards of W3C. As the first important cornerstone of the next generation Web, XML provides powerful functions for distributed and heterogeneous data exchange, separating the data itself from its representation. At the same time, as far as the data itself is concerned, the value and semantics of the data are also properly separated. In fact, XML Base has developed into a family of technologies, including XML Schema released in May 2006, XML Namespaces released in June, XSLT released in June to handle XML transformation, XPath released in June to locate XML documents, and 2000. In addition, the appearance of XML provides a common foundation for programs to automatically process Web data and information and Web services (WSDL, SOAP, UDDI specifications).
* DOM:DOM provides a basic object model for the processing of data carriers and information carriers such as HTML and XML in memory, and can provide the structure, format and events connected to files. Because it does not depend on any programming language or web page description language, it provides a standard and independent interface for effectively processing HTML and XML data. DOM has gone through three versions, namely1DOM Level 1 released in June 1998, DOM Level 2 released in June 2000 and DOM Level 3 released in October 2003.
* MathML:MathML provides a tool language to realize cross-platform mathematical description mechanism on the Web. MathML has been released in two versions:10 in July 1999 and MathML 2.0 in February 2006.
* PNG (Portable Network Graphics): PNG released by 1996 is a portable image document format, which has no influence on graphic pixels and is convenient for image compression. At present, it is one of the most widely used Web image formats.
* SVG (Scalable Vector Graphics): SVG is an image content management mechanism for a large number of vector graphics on the Web, including image content query, customization and image use. In September 2006, 5438+0, SVG 1.0, SVG1.SVG Basic and Tiny have been able to provide vector images for some small devices. The draft SVG 1.2 was submitted in July 2003.
* RDF (Resource Description Framework): RDF is the first recommended standard for building semantic networks. It provides technical standards for describing characters, codes and metadata on the Web, and establishes the relationship between these objects and rich resources on the Web. RDF was released in February 1999, and it is still the most important technical standard of semantic web and one of the foundations of other technologies.
W3C CSS verification service is a free software produced by W3C to help web designers check cascading style sheets (CSS). You can use it in the free online service provided by W3C, or download it and run it as a Java program or Servlet on your own machine.
Web2.0 is an upgrade of Web 1.0 with different versions.
In Web 1.0, Internet content is customized by a few editors (or webmasters), such as Sohu; In Web2.0, everyone is a contributor to the content. The content of Web2.0 is more diverse: tags, multimedia, online collaboration and so on. RSS subscription plays a very important role in Web2.0 information acquisition channels. I also always recommend readers to subscribe to reading articles.
In Web 1.0, the Internet is "reading Internet" and Web2.0 is "writable and readable Internet". Although everyone participates in information feed, on a large scale, it is a few people who contribute most of the content.
Web2.0 actually expands the information source of Web 1.0, making it diversified and personalized.
AJAX is called "asynchronous JavaScript and XML", which refers to a web development technology for creating interactive web applications. The common pronunciation in China is "Ajax", which is the same as the pronunciation of Ajax football team.
The definition of Ajax
XHTML+CSS representation based on web standard representation;
Use DOM (Document Object Model) for dynamic display and interaction;
Use XML and XSLT for data exchange and related operations;
Asynchronous data query and retrieval using XMLHttpRequest;
Use JavaScript to bind everything together. In English, please see the original text and title of Jesse James Garrett, the originator of Ajax (Ajax: a new method of web application).
Similar to DHTML or LAMP, AJAX does not refer to a single technology, but uses a series of related technologies organically. In fact, some AJAX-based "derivative/composite" technologies are emerging, such as "AFLAX".
The application of AJAX uses a web browser supporting the above technology as the running platform. These browsers currently include Mozilla, Firefox, Internet Explorer, Opera, Konqueror and Safari. But Opera does not support XSL format objects, nor does it support XSLT.
AJAX has a very optimistic prospect, which can improve the system performance and optimize the user interface. AjaxPro, the existing direct framework of AJAX, can import AjaxPro.2.dll files, and can directly call the background page method on the foreground page JS. However, this framework conflicts with form validation. In addition, Microsoft also introduced AJAX, which requires adding AjaxControlToolkit.dll files, and related controls can appear in the list of controls.
JS is short for JavaScript. A computer scripting language, which is mainly interpreted and executed in web browsers (clients) and developed by Netscape.
The word seo is taken from the initials of English search engine optimization, which is a popular online marketing method in recent years. Its main purpose is to increase the exposure of specific keywords to increase the popularity of the website, and then increase sales opportunities. SEO of a website refers to making the content of the website easier to be obtained and accepted by search engines. After receiving the information of websites, search engines compare and calculate, and then put the websites with higher weight in the priority position that other users will give when searching on the network, thus prompting searchers to get correct and helpful information.
The main work of SEO is to understand how various search engines grab Internet pages, how to index them, and how to determine their ranking of search results for a specific keyword, so as to optimize web pages and improve the ranking of search engines, thereby increasing the number of visitors to the website and ultimately improving the sales or publicity capabilities of the website.
Browser is a kind of software that displays files in a web server or file system and allows users to interact with these files. It is used to display text, images and other information on the World Wide Web or LAN. These words or images can be hyperlinked to other websites, and users can browse all kinds of information quickly and conveniently.
Common web browsers on personal computers include Microsoft's Internet Explorer, Mozilla's Firefox, Apple's Safari, Opera, HotBrowser and Google's Chrome.
The difference between browsers depends on the kernel:
Trident: the kernel used by IE browser. This kernel program was first adopted in IE4 of 1997. It was modified by Microsoft on the basis of mosaic code and has been used in IE7. Trident is actually an open kernel, and its interface kernel is quite mature, so many browsers (such as Maxthon, Tianxia, TT, GreenBrowser, AvantBrowser, etc.) use IE kernel instead of IE. In addition, for convenience, many people simply call it IE kernel (of course, it is not excluded that some people have to say this because they don't know the kernel name).
Due to the "monopoly" of IE itself (although IE is not a monopoly in name, in fact, especially from the 1990s of Windows to the early days of XP, IE was really in a "monopoly" position with the help of the east wind of Windows), the Trident kernel has occupied a dominant position for a long time. Microsoft hasn't updated the Trident kernel for a long time. This leads to two consequences-one is that Trident kernel is almost out of line with W3C standard (2005), the other is that a large number of bugs and other security problems in Trident kernel have not been solved in time, and then some developers and scholars who are committed to open source openly think that IE browser is unsafe, and many users turn to other browsers. This is when Firefox and Opera appeared. The market share of non-Trident kernel browsers has increased greatly, and many web developers have begun to pay attention to the browsing effect of web standards and non-IE browsers.
Geckos: The kernel adopted by Netscape 6 and later adopted by Mozilla FireFox. Geckos is characterized by completely open code, so it is very developable, and programmers all over the world can write code and add functions for it. Because it is an open source kernel, it is favored by many people, and there are many browsers for Geckos kernel, which is also an important reason why Geckos kernel can rapidly increase its market share although it is young.
In fact, the origin of gecko engine is related to IE. As mentioned earlier, IE did not use W3C standard, which led to the dissatisfaction of some developers inside Microsoft. Together with some employees of Netscape who had stopped updating at that time, they founded Mozilla, rewritten the kernel based on the mosaic kernel at that time, and developed the gecko. But in fact, the browser of gecko kernel is still the most user of Firefox, so it is sometimes called Firefox kernel. Gecko is also a cross-platform kernel, which can be used in Windows, BSD, Linux and Mac OS X.
Presto: The kernel currently used by Opera, which was first used in Opera7 in 2003. The feature of this engine is that the rendering speed is optimized to the extreme, and it is also recognized as the browser kernel with the fastest web browsing speed at present, but at the expense of web compatibility.
In fact, this is a dynamic kernel, and the biggest difference from the previous kernel lies in script processing. Presto has a natural advantage that it can reparse all or part of a page in response to script events. In addition, this kernel is the fastest when executing javascr and pt. According to the test under the same conditions, the time required for Presto kernel to execute equivalent javascr and pt is only about 1/3 of that of Trident and Gecko kernels (Trident kernel is the slowest, but there is little difference between them). In that test, because the hardware condition of Apple computer is different from that of ordinary PC, the WebCore kernel was not tested. Unfortunately, Presto is a business engine. Besides Opera, only NDSBrowser, Wii Internet Channel and Nokia 770 Web Browser are used in Presto, which greatly limits the development of Presto.
Webkit: Apple's own kernel is also used by Apple's Safari browser. Webkit engine includes WebCore typesetting engine and JavaScriptCore parsing engine, both of which are derived from KDE's KHTML and KJS engines. They are free software, authorized by GPL protocol, and support the development of BSD system. So Webkit is also free software and open source code. In terms of security, it is not restricted by IE and Firefox, so Safari browser is still very safe in China.
Limited to the limited use of Mac OS X and Safari browser used to be the exclusive browser of Mac OS X, the kernel itself should be said that the market scope is not large; However, according to the latest browser survey, the market of this browser seems to have even surpassed that of Opera's Presto-of course, this is because Apple's popularity soared after switching to x86 architecture, and also because Safari 3 finally launched the Windows version. Because Apple recently ported Safari to Windows, there are no other browsers using WebKit on Windows for the time being, but there are also popular browsers such as OmniWeb and Shiira under Mac.
XML (Extensible Markup Language) is an extensible markup language. Like HTML, it is SGML (Standard generalized markup language). Xml is a cross-platform and content-related technology under the Internet environment, and it is a powerful tool for processing structured document information at present. XML is a simple data storage language, which uses a series of simple tags to describe data, and these tags can be established in a convenient way. Although XML takes up more space than binary data, it is very simple and easy to master and use.
XML is different from databases such as Access, Oracle and SQL Server. Database provides more powerful data storage and analysis capabilities, such as data indexing, sorting, searching, association consistency and so on. XML only displays data. In fact, the biggest difference between XML and other data representations is that it is extremely simple This may seem like a trivial advantage, but it is this that makes XML unique.
The design difference between XML and HTML is that XML is used to store data, and it focuses on the data itself. HTML is used to define data, and the focus is on the way data is displayed.
The simplicity of XML makes it easy to read and write data in any application, which soon makes XML the only universal language for data exchange. Although different applications also support other data exchange formats, in the near future, they will all support XML, which means that programs can be more easily combined with information generated under Windows, Mac OS, Linux and other platforms, and then XML data can be easily loaded into programs and analyzed, and the results can be output in XML format.
In order to make SGML user-friendly, XML redefines some internal values and parameters of SGML, and removes many rarely used functions. These complex functions make SGML complicated when designing websites. XML retains the structural function of SGML, which enables website designers to define their own document types. At the same time, XML also introduces a new document type, so that developers don't have to define document types.
Because XML is formulated by W3C, the standardization of XML is the responsibility of W3C's XML working group, which is composed of experts from various places and industries. They exchanged their views on XML standards by email and put forward their own opinions (www.w3.org/TR/WD-xml). Because XML is a public format (not owned by any company), you don't have to worry that XML technology will become a profit tool for a few companies. XML is not a language that is attached to a specific browser.