html5
HTML5 is the latest and most enhanced version of HTML. Technically, HTML is not a
programming language, but rather a markup language. This tutorial gives very good
understanding on HTML5.
HTML5 Overview
HTML5 is the next major revision of the HTML standard superseding HTML 4.01, XHTML 1.0, and
XHTML 1.1. HTML5 is a standard for structuring and presenting content on the World Wide Web.
HTML5 is a cooperation between the World Wide Web Consortium (W3C) and the Web Hypertext
Application Technology Working Group (WHATWG).
The new standard incorporates features like video playback and drag-and-drop that have been
previously dependent on third-party browser plug-ins such as Adobe Flash, Microsoft Silverlight,
and Google Gears.
Browser Support:
The latest versions of Apple Safari, Google Chrome, Mozilla Firefox, and Opera all support many
HTML5 features and Internet Explorer 9.0 will also have support for some HTML5 functionality.
The mobile web browsers that come pre-installed on iPhones, iPads, and Android phones all
have excellent support for HTML5.
New Features:
HTML5 introduces a number of new elements and attributes that helps in building a modern
websites. Following are great features introduced in HTML5.
New Semantic Elements: These are like <header>, <footer>, and <section>.
Forms 2.0: Improvements to HTML web forms where new attributes have been
introduced for <input> tag.
Persistent Local Storage: To achieve without resorting to third-party plugins.
WebSocket : A a next-generation bidirectional communication technology for web
applications.
Server-Sent Events: HTML5 introduces events which flow from web server to the web
browsers and they are called Server-Sent Events (SSE).
Canvas: This supports a two-dimensional drawing surface that you can program with
JavaScript.
Audio & Video: You can embed audio or video on your web pages without resorting to
third-party plugins.
Geolocation: Now visitors can choose to share their physical location with your web
application.
Microdata: This lets you create your own vocabularies beyond HTML5 and extend your
web pages with custom semantics.
Drag and drop: Drag and drop the items from one location to another location on a
the same webpage.
Backward Compatibility
HTML5 is designed, as much as possible, to be backward compatible with existing web browsers.
New features build on existing features and allow you to provide fallback content for older
browsers.
It is suggested to detect support for individual HTML5 features using a few lines of JavaScript.
If you are not familiar with any previous version of HTML, I would recommend to go through our
HTML Tutorial before you explore further concepts of HTM5.
HTML5 Syntax
The HTML 5 language has a "custom" HTML syntax that is compatible with HTML 4 and XHTML1
documents published on the Web, but is not compatible with the more esoteric SGML features of
HTML 4.
HTML 5 does not have the same syntax rules as XHTML where we needed lower case tag
names, quoting our attributes,an attribute had to have a value and to close all empty elements.
But HTML5 is coming with lots of flexibility and would support the followings:
Uppercase tag names.
Quotes are optional for attributes.
Attribute values are optional.
Closing empty elements are optional.
The DOCTYPE:
DOCTYPEs in older versions of HTML were longer because the HTML language was SGML based
and therefore required a reference to a DTD.
HTML 5 authors would use simple syntax to specify DOCTYPE as follows:
<!DOCTYPE html>
All the above syntax is case-insensitive.
Character Encoding:
HTML 5 authors can use simple syntax to specify Character Encoding as follows:
<meta charset="UTF-8">
All the above syntax is case-insensitive.
The <script> tag:
It's common practice to add a type attribute with a value of "text/javascript" to script elements
as follows:
<script type="text/javascript" src="scriptfile.js"></script>
HTML 5 removes extra information required and you can use simply following syntax:
<script src="scriptfile.js"></script>
The <link> tag:
So far you were writing <link> as follows:
<link rel="stylesheet" type="text/css" href="stylefile.css">
HTML 5 removes extra information required and you can use simply following syntax:
<link rel="stylesheet" href="stylefile.css">
HTML5 Elements:
HTML5 elements are marked up using start tags and end tags. Tags are delimited using angle
brackets with the tag name in between.
The difference between start tags and end tags is that the latter includes a slash before the tag
name.
Following is the example of an HTML5 element:
<p>...</p>
HTML5 tag names are case insensitive and may be written in all uppercase or mixed case,
although the most common convention is to stick with lowercase.
Most of the elements contain some content like <p>...</p> contains a paragraph. Some
elements, however, are forbidden from containing any content at all and these are known as
void elements. For example, br, hr, link and meta etc.
HTML5 Attributes:
Elements may contain attributes that are used to set various properties of an element.
Some attributes are defined globally and can be used on any element, while others are defined
for specific elements only. All attributes have a name and a value and look like as shown below
in the example.
Following is the example of an HTML5 attributes which illustrates how to mark up a div element
with an attribute named class using a value of "example":
<div class="example">...</div>
Attributes may only be specified within start tags and must never be used in end tags.
HTML5 attributes are case insensitive and may be written in all uppercase or mixed case,
although the most common convention is to stick with lowercase.
HTML5 Document:
The following tags have been introduced for better structure:
section: This tag represents a generic document or application section. It can be used
together with h1-h6 to indicate the document structure.
article: This tag represents an independent piece of content of a document, such as a
blog entry or newspaper article.
aside: This tag represents a piece of content that is only slightly related to the rest of
the page.
header: This tag represents the header of a section.
footer: This tag represents a footer for a section and can contain information about the
author, copyright information, et cetera.
nav: This tag represents a section of the document intended for navigation.
dialog: This tag can be used to mark up a conversation.
figure: This tag can be used to associate a caption together with some embedded
content, such as a graphic or video.
The markup for an HTM 5 document would look like the following:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>...</title>
</head>
<body>
<header>...</header>
<nav>...</nav>
<article>
<section>
...
</section>
</article>
<aside>...</aside>
<footer>...</footer>
</body>
HTML5 Attributes
As explained in previous chapter, elements may contain attributes that are used to set various
properties of an element.
Some attributes are defined globally and can be used on any element, while others are defined
for specific elements only. All attributes have a name and a value and look like as shown below
in the example.
Following is the example of an HTML5 attributes which illustrates how to mark up a div element
with an attribute named class using a value of "example":
<div class="example">...</div>
Attributes may only be specified within start tags and must never be used in end tags.
HTML5 attributes are case insensitive and may be written in all uppercase or mixed case,
although the most common convention is to stick with lowercase.
Standard Attributes:
The attributes listed below are supported by almost all the HTML 5 tags.
Attribute Options Function
accesskey User Defined Specifies a keyboard shortcut to access an element.
align right, left, center Horizontally aligns tags
background URL Places an background image behind an element
bgcolor numeric, hexidecimal, Places a background color behind an element
RGB values
class User Defined Classifies an element for use with Cascading Style
Sheets.
contenteditable true, false Specifies if the user can edit the element's content or
not.
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