Basically HTML5 has it’s many new syntactical features, which include the , , and elements, as well as the integration of SVG content. Due to these new elements, it will be very easy to integrate multimedia and graphical content to web without using flash and third party plugins. There are also another new elements like , , and which enrich the semantic value of the document. Other major advantages of HTML5 are described below.

1. Mutuality

Due to usability purpose the web sites made by developers are highly interactive nowadays and for this developers need to include fluid animations, stream video, play music and Social Network sites like Facebook and Twitter into the websites. Till now they have only the option to integrate it with the help of Flash or Silverlight, Flex or javascript like tools. But these consume so much time to develop and even the complexity of web application also increased. But now with the help of HTML5 it is possible to embed video and audio, high quality drawings, charts and animation and many other rich content without using any plugins and third party programmas as the functionality is built into the browser.

2. Cleaner markup / Improved Code

HTML 5 will enable web designers to use cleaner, neater code, we can remove most div tags and replace them with semantic HTML 5 elements.
3. Improved Semantics

Now it is easy to see which parts of the page are headers, nav, footers, aside, etc as the tags are specific for these all and most importantly know what their meaning and purpose is in whole the format. By using HTML5 elements we can increase the semantic value of the web page as the codes are very standardized.
4. Elegant forms

HTML5 enables designer to use more fancier forms. Even it makes form validation native to HTML, User interface enhancements and reduced need for JavaScript (only needed in browsers that don’t support form types). There will be different type of text inputs, search and different fields for different purpose.
5. Consistency

As websites adopt the new HTML5 elements we will see more greater consistency in terms of the HTML used to code a web page on one site compared to another. This will make it more easier for designers and developers to immediately understand how a web page is structured.
6. Improved Accessibility

Different technologies can elaborate on the features with the help of HTML5, as they can Immediately make more detailed understanding of the structure of a page by take a look at HTML5 elements it has.
7. Fulfill the need of Web application

Many new features and standards have emerged as part of HTML 5. Once you detect the available features in today’s browsers, you can take advantage of those features in your application. Main focus of HTML5 is to make easier application with easy front-ends, drag and drop tools, discussion boards, wikis and other useful elements.
8. Offline Application cache

All browsers have some kind of caching m After a sometime, you open up your laptop and click the Back button in the browser hoping to see the previous page that was opened. However, as you are not connected to the internet and the browser didn’t cache the page properly, you are unable to view that page. You then click the Forward button thinking that at least that page will load, but it doesn’t. You need to reconnect to the internet to be able to view the pages. HTML 5, thankfully, provides a smarter solution. While building the site, the developer can specify the files that the browser should cache. So, even if you refresh the page when you are offline, the page will still load correctly. This sort of caching has several advantages like offline browsing, files load much faster and reduced load on server
9. Client-side database

While cookies have been used to track unique user data for years, they have serious disadvantages. The largest flaw is that all of your cookie data is added to every HTTP request header. This can end up having a measurable impact on response time. So a best practice is to reduce cookie size. With HTML5 we can do better by using sessionStorage and localStorage(two different storage in HTML5) in place of cookies. It is not a permanent database, but enables you to store structured data, temporarily.
10. Geolocation support

With help of Geolocation any one can find out where you are in the world and sharing that information with people. There is different ways to figure out where you are — your IP address, your wireless network connection, which cell tower your phone is talking to, or dedicated GPS hardware that calculates latitude and longitude from information sent by satellites in the sky. But The new HTML5 geolocation APIs make location, whether generated via GPS or other methods, directly available to any HTML5-compatible browser-based application.

This is only the overview of the HTML5 advantages, actually there is lots more to know about HTML5. In the near future HTML5 will become a online development language. It is assumed that it will not completely finished before 2022.So just keep it in your mind and start using HTML5 in your designs right now!
- See more at: http://www.html5arena.com/blog/html5/10-major-advantages-of-html5/#sthash.rtYmKpTY.dpuf