Structure and semantics of HTML5-preface (1)

Hypertext Markup Language (HTML) 5 introduces new elements to HTML for the first time. The new structure elements include aside, figure, and section. New inline elements include time, meter, and SS. New embedded elements include video and audio. New interaction elements include details, datagrid, and command.
 
The development of Hypertext Markup Language (HTML) ended in HTML 4 in 1999. The World Wide Web Consortium (W3C) has shifted its focus to converting the underlying HTML syntax from a standard generic Markup Language (SGML) to a scalable markup language (XML) and a scalable vector graph (SVG), XForms, and MathML are all new Markup languages. Browser vendors focus on browser features such as tabs and rich site abstract (RSS) readers. Web designers began to learn how to use Asynchronous JavaScript XML (Ajax). Under the existing framework, they can use Cascading Style Sheets (CSS) and JavaScript? Language to build your own applications. However, in the next eight years, HTML has not changed.
 
Recently, it has been revived. Three major browser vendors-Apple, Opera, and Mozilla Foundation-have established the Web Hypertext Application Technology Working Group (WhatWG) to develop new versions of traditional HTML. Recently, W3C has paid attention to these activities and launched its own new-generation HTML project. Many members of both parties are the same. These two projects may eventually be merged. Although many details are still under discussion, the general outline of the next version of HTML is clear.
 
Since 1999, Web developers have been expecting a new version of HTML (commonly known as HTML 5, but also known as Web Applications 1.0). Now it has finally been released. It maintains the original characteristics of HTML: No namespace or mode. The element does not have to end. The browser treats errors with tolerance. P is still p, and table is still table.
 
If a Web developer was frozen in 1999 and then restored, he would encounter some new confusing elements. Yes, the elements he is familiar with (such as div) are retained. However, HTML still contains new elements such as section, header, footer, and nav. Em, code, and strong still exist, but meter, time, and m are added. Img and embed are still available, but video and audio are also added. However, after careful observation, he will find that these elements are actually no different. Many of these elements may not be available to developers in 1999. Through a simple analogy with the elements he has mastered, these new elements are easy to understand. In fact, they are much easier to grasp than Ajax or CSS.
 
Finally, when he turned on his 300 MHz notebook (running Windows 98 and frozen in 1999), he may be directed to Netscape 4 and Windows? Internet Explorer? 5. The effect of the new page is surprising. Of course, these old browsers are not familiar with new elements and will ignore them completely, but the page will still display and the content will still be complete.
 
This is not a fictitious story. The design principle of HTML 5 is that it can be smoothly degraded in browsers that do not support it. The reason is simple: we are all such "primitive people ". The browser now has tabs, CSS, and XmlHttpRequest, but their HTML Display Engine remains at the level of 1999. In addition to the large increase in the number of users, there is actually no progress in Web. This is taken into account in HTML 5. Currently, it provides some real benefits for Web developers. With the slow upgrade of browsers, page viewers will gradually enjoy these benefits.
 
Let's take a look at what HTML 5 provides