An Overview of HTML5
With HTML5, developers can create apps and websites that function like desktop applications, which allows you to use the web platform to reach all of your users at once. Users no longer have to download apps for multiple devices, They can start an app by clicking on a link or button and not have to worry about having the latest update.
An interesting aspect of HTML5 is that it will allow you to create apps that function even when not connected, or when your system is offline. The trick is being able to store the assets and content locally. When this is done, the app works, regardless of where you go or if your system is online. Another one of the positive aspects of the offline features is being able to store data in the cache or in such a way that allows the data to be retained even if the page is reloaded.
HTML5 tags are backwards compatible so that HTML 4-based content won't destroy HTML5 content. The former HTML structure and formatting is retained.
HTML5 allows you to embed video directly into a web page. Be aware that while the video element has been standardized, how the video codec is supported varies with each browser, so it's important to check that as part of your development process.
New types of form elements have been included, which allow you to display a given type of input then rely upon the browser to execute it. Some of the input options are: Telephone number, email, URL, date, time, color along with different variations.
Semantic markup tags are another advance which allow to structure your content so that the structure has meaning, sometimes known as semantics. Examples of this are the: <article> , <section> , <header> , <footer> , <aside> , <nav> , and <figure> tags. This allows you to place important elements into sections. It's also useful for search engines and aggregators.
The DOCTYPE has been simplified. The result is that HTML5 documents are valid XML structures. HTML5 content is XML based which means that it must follow XML formatting rules.
It's important to realize that while HTML5 isn't standardized it is in use on devices such as the Apple iOS, Android, BlackBerry 6, and HP/Palm WebOS devices. All of the major browsers (Safari, Chrome, Opera, Internet Explorer) support HTML5, but it's not equal across platforms, so it's important to test out the features on the different devices, platforms, etc. To make sure that you're obtaining the results you seek, it would be wise to get feedback from users during the course of development.
• For an in-depth look at how HTML5 differs from HTML4, have a look at: HTML5 Differences from HTML4