An overview of HTML5

HTML5 is the core language of the World Wide Web, the fifth major modification to the application of Hypertext Markup Language (HTML) in the standard Universal markup Language, the latest version of the Hypertext Markup language following HTML4.01 and XHTML1.0. It is designed by a group of free thinkers, and ultimately enables multimedia support, interactivity, smarter forms, and better semantic tagging.

HTML5 is not only the latest version of the HTML specification, but also a series of related technologies used to make modern rich web content, the most important of the three technologies are:HTML5 core Specification (tag Element), CSS (third generation of cascading style sheets), and JavaScript.

I. History of HTML5 Development

The 1993 HTML was first published in the form of an Internet draft, and then went through 2.0, 3.2, and 4.0, until the HTML4.01 version of 1999 stabilized. Gradually replaced by stricter XHTML because of the slow development.

XHTML is an HTML version of XML-based, dedicated to stricter and uniform coding specifications, and the web developer has greatly embraced XHTML because of the odd behavior of the browser due to the non-canonical encoding of the previous HTML4.01 version. The great advantage of XHTML is to force developers to develop good coding habits, discard HTML clutter, and ultimately reduce the difficulty of browser parsing pages, and facilitate porting to more platforms.

However, the more you want to develop in the good, often can bring a devastating disaster, the world is so. XHTML2.0 specifications for stricter error handling rules, forcing browsers to reject invalid XHTML2 pages, forcing web developers to write code that is absolutely correct and not backwards compatible, discarding HTML-first-class quirks and coding habits. Supposedly, taking its essence to its dross is a good thing, but so that the familiar pages can not be compatible, the difficulty of web developers have been increased, and set this standard is too long, eventually abandoned.

2008 the World Wide Web published HTML5 work Draft, 2009 stopped XHTML2.0 plan, and in the past about a year, HTML5 specification further solved many very practical problems, major browser manufacturers began to upgrade their products to support HTML5. Thanks to the browser's experimental feedback, the HTML5 specification has been continuously improved and perfected, which quickly integrates into the substantive improvements of the Web platform.

Unlike XHTML2.0, a group of people who make HTML5 specifications do not want to pick out the various defects of the previous HTML for their correction, but as much as possible to complement the full web development needs of the various functions. These features include more powerful CSS3, form validation, audio and video, local storage, geolocation, painting (Canvas), web communication, and more.

Second, HTML5 function

1.HTML5 Core: This part is mainly made up of official specifications, designing new semantic elements, new enhanced Web Forms, audio and video, and canvas drawing through JavaScript. This part of the majority of mainstream browsers are very good support.

2. The HTML5 standard: This part comes primarily from the HTML5 specification that was originally developed, most of which require JavaScript and support rich Web application development. For example: Local data storage, offline applications, and messaging.

3. Non-HTML5 standard: This part usually refers to the next generation function, although never entered the HTML standard, but people still recognize it as part of the HTML5. These include the most common CSS3, as well as the very popular geographical location.

For the most common and useful parts, basically the mainstream browser support is relatively good. And the special needs of the part, you need to be based on different browser detection to know whether to support their own desired features.

Three, the characteristics of HTML5

1. Backwards compatibility

HTML5 implements the "Do not destroy the Web" principle, that is to say, the previous existing pages, but also to maintain the correct display.

In the face of developers, the HTML5 specification calls for the rejection of past coding bad habits and discarded tag elements, while facing browser vendors, they are required to be compatible with HTML and everything, in order to achieve backwards compatibility.

2. User first

HTML5 follow the "user first" principle, in the case of specific problems, will put the user in the first place, followed by the developer, then the browser manufacturer, and finally the norm-makers. For example, when the developer is not strict with the code, the warning or error should appear, but the page is displayed normally.

3. Simplify the complex

HTML5 has done a lot of simplification in comparison to the previous XHTML, specifically as follows:

(1) Replace the complex JavaScript with the native ability of the browser;

(2) DOCTYPE is simplified to the extreme;

(3) Character set declaration is simplified;

(4) Simple and powerful API.

4. No plug-in paradigm

Before HTML5, many features can only be implemented through plugins or hack (such as the drawing API), but HTML5 native provides these support. There are many problems with plugins, as follows:

(1) Plug-in installation is easy to fail;

(2) The plugin is disabled by the browser or software (such as Flash plugin);

(3) Plug-ins are often exploited to exploit exploits;

(4) Plugins are not easy to integrate with other parts of the HTML document (such as overall transparency).

5. Access Versatility

(1) Accessibility: For example, more conducive to the reading program for people with disabilities;

(2) Media neutrality: such as HTML5 media broadcast in different sets or different platforms can be normal operation;

(3) Support all languages: such as new element <ruby>.

6. Introducing Semantics

HTML5 introduces some markup elements to differentiate between different meanings and different content. This approach greatly provides the readability of the coding staff and the convenience of the Code area query.

7. Introduction of native Media support

A big improvement in HTML5 is the ability to play video and audio files directly in the browser, previously requiring plug-ins to achieve such functionality.

8. Introduction of programmable Content

The biggest change in HTML5 is the introduction of various effects that need to be programmed by JavaScript, many of which are HTML5 native. So now HTML5 can be understood as the general term of Html+css+javascript.

An overview of HTML5