Is HTML5 tags are available in all browsers.

Answer 1

Not all of them. This website http://html5please.com is really helpful or this http://www.w3schools.com/html/html5_new_elements.asp .

Answer 2

Its a bit more complicated than just saying a browser supports it or not, as different parts of HTML5 can be support on a specific browser. Here is a good resource for mobile browsers: http://mobilehtml5.org/ I am sure there is an equivalent for desktop.

Answer 3

I find http://caniuse.com/ very useeful to check the new features for browser support.