That's a useful feature, but when can I use it?
An understandable reaction many people have when they realise they can’t use a certain feature of HTML, CSS or other web technologies is to blame the W3C for being slow. Sometimes doing so may be correct, but a lot of the time it is browser vendors who are slow to implement emerging standards.
Keeping track of which browsers—and from which version—support a particular recommendation or standard is no easy task. But there is help. Alexis Deveria’s When can I use… contains a lot of compatibility tables for features in HTML5, CSS3, SVG and other upcoming web technologies.
Don’t need to see the whole lot? Only want to check the status for standards that have Recommendation status? Not interested in what really old browsers (do not) support? No problem—just use the filters at the top of the page to pick what interests you.
Needless to say, these compatibility tables make it very obvious which browser vendors are quick to implement new technologies and which are a little slower.