Is HTML 5 supported by all the main browsers?

Question

I am looking at the custom attributes feature of html 5 here at this link http://ejohn.org/blog/html-5-data-attributes/

This look like the perfect thing for when

Answer 1

Parts of HTML 5 are supported by Safari, Firefox and Opera, but they are not necessarily incorporating the same parts.

It seems that Firefox is the most ahead, from my experience, but it will be years before the majority of browsers users use will support it.

So, until then we will need to continue trying to use it when we can, in browsers that support the new features, and having workarounds for users that haven't updated yet, or continue to use IE.