HTML5 is a relatively young specification, and as a result, browser support is quite limited (at the time of writing). Main features will work in all browsers, but some will not. Here are several charts about how well each browser supports HTML5 and CSS3. To ensure that you can experience all of HTML 5 new features, it is recommended that you install the latest versions of the following Web browsers on your system:
Mozilla Firefox (version 3.6/4)
Apple Safari (version 5)
Opera (version 10/11)
Google Chrome (version 7/9/10)
However, since old versions of the browsers won’t support HTML5 or CSS3, you can still make your site work by what is known as: Progressive Enhancement and Graceful Degradation
Has the Prime Time come for HTML 5?
There is a lot of confusion about the future of the web and HTML5. HTML5 has been THE buzzword in web technologies for the past couple of years, and each year the excitement grows even larger. We are told that we will no longer need Flash, embedding videos will be easy, and we will be able to have advertising without third-party plugins. We are told that HTML5 will be the magic fix to all of our development woes, and never again will we struggle to create the next great multimillion dollar web site.
Not so fast. If it sounds to good to be true…well, you know.
There a lot of good reasons to implement HTML5 today. There are also a lot of good reasons not to, including the fact the HTML5 is not a finalized standard by the W3C. Whatever you decide on implementing HTML5, the decision you make will have consequences immediately for your site. And not all of those consequences are positive.