1th Chapter HTML5 Overview

Learning Essentials:

The history of 1.HTML5
Features of the 2.HTML5
Features of 3.HTML5
4. Course Learning Issues

Keynote Teacher: Li Tinghui

HTML5 is the latest version of 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 just the latest version of the HTML specification, but rather a series of related technologies used to make modern, rich Web content, the most important of which are: the HTML5 core specification (tag Element), CSS (third generation of cascading stylesheets), and JavaScript.

A The history of HTML5
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. Due to the slow development, gradually replaced by more stringent XHTML.

The Sovranty of XHTML
Since the HTML4.01 version, the World Wide Web Consortium, which has mastered the HTML specification, has not released new standards, but has been working around XHTML1.0 and later XHTML2.0. XHTML is an HTML version of XML-based, dedicated to stricter and uniform coding specifications, and when it comes to resolving previous versions of HTML4.01, the browser's quirky behavior is caused by nonstandard coding. As a result, Web developers have embraced XHTML very much. The great advantage of XHTML is to force developers to develop good coding habits, abandon the messy writing of HTML, 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, it is often possible to bring a devastating disaster, the world is so. XHTML2.0 the stricter error-handling rules, forcing the browser to reject invalid XHTML2 pages, forcing WEB developers to write code that is absolutely correct and not backwards compatible, discarding the weird behavior and coding habits that HTML left behind. It should be good to take its essence and discard its dross. However, in this case, hundreds of millions of of the page will not be compatible, the difficulty of the WEB developer has been increased, and the formulation of this standard is too long, eventually abandoned.

The return of HTML5
In 2008, the HTML5 's work was released and the XHTML2 plan was discontinued in 2009. Over the past year or so, the HTML5 specification further solves many very practical problems, with major browser vendors starting to upgrade their products to support HTML5. In this way, thanks to the browser's experimental feedback, the HTML5 specification has been continuously improved and perfected to quickly integrate 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 usual flaws of HTML to correct them, but as much as possible to complement the needs of the WEB developers of all kinds of functions. These features include more powerful CSS3, form validation, audio and video, local storage, geolocation, painting (Canvas), web communication, and more.

Two Features of the HTML5
What features does the HTML5 cover? How are these features supported in the mainstream browser?
　　1.HTML5 Core : This part is mainly made up of official specifications, involving new semantic elements, new enhanced Web Forms, audio and video, and Canvas drawing through JavaScript. This part of the majority of mainstream browsers are well supported;
　　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 application and message delivery; 3. Non-HTML5 standard: This part usually refers to the next generation function, although never entered the HTML5 standard, but people will still recognize it as part of 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 Features of HTML5
HTML5 development at the same time, XHTML2.0 is also constantly developing, then what is the characteristics of the HTML5 to achieve the ultimate victory?

　　1. Backwards compatibility
For XHTML2.0 requirements to follow the rules, otherwise not show the way, HTML5 "Do not destroy the Web" principle. That is, Web pages that existed before can still be displayed correctly.
Of course, 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 all HTML legacy 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, a developer who is not rigorous in coding causes a warning or error to appear, but the page is displayed normally.

　　3. Simplify the complex
HTML5 compared to the previous XHTML, did a lot of simplifying work. Specific as follows:
(1). Replace the complex JavaScript with the native ability of the browser;
(2). DOCTYPE is simplified to the extreme;
(3). Character set declarations are simplified;
(4). Simple and powerful API.

　　4. No plug-in paradigm
Before the advent of HTML5, many features could only be implemented through plugins or hack (such as the drawing API), but HTML5 native provided these support. There are many problems with plugins, as follows:
(1). Plug-in installation is easy to fail;
(2). Plugins are 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
This principle consists of three concepts:
(1). Accessibility: For example, reading programs that are more conducive to people with disabilities;
(2). Media Neutrality: For example, HTML5 media playback can operate normally on different devices or platforms;
(3). Support All languages: such as new element <ruby>.

　　6. Introducing Semantics
HTML5 introduces a number of markup elements used to differentiate between different meanings and 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 the life vest supports the ability to play video and audio files directly in the browser, previously requiring plug-ins to enable such functionality.

　　8. Introduction of programmable Content
The biggest change in HTML5 is the introduction of a variety of effects that need to be programmed with JavaScript, many of which are HTML5 native. Now HTML5 can be understood as the generic term for HTML + CSS + JavaScript.

Four Course Learning Issues
Learning HTML5 requires a number of test browsers, coding development tools, and recommended learning methods.

　　1. Browser selection

ie9+
Firefox 3.5+
Chrome 3.0+
Safari 3.0+
Opera 10.5+

Here is the main point to explain the IE browser. Due to historical and system binding reasons, there are a significant portion of the computer remaining IE9 the following versions of the browser. Although Microsoft has begun to make a statement to gradually no longer maintain the IE8, but this part of the group also occupies a certain share. Therefore, whether to cater to this part of the user depends on the individual's judgment on the market and the cost of consideration.

　　2. Development tools
In this course we use Sublime TEXT3 as the coding tool for the HTML5 course. Uses Soda Dark 3 as the theme of the software interface.

　　3. Learning Style
This course is 0 basic and beginner, but if you already have an XHTML course foundation, it's easy to learn. Of course, although we have already recorded the XHTML Foundation, when we record the HTML5 course, we treat all the students as beginners who are just in touch. Again of course, here is said 0 basic and beginners also need certain experience, because of long-term teaching work, we contact many even QQ will not use, mail will not send, Thunderbolt will not download students. These students are pre-beginners, negative basis of the students, so if it is beginner general problems.

1th Chapter HTML5 Overview