In general, I think the web has decent backwards compatibility. With a few exceptions, websites from ten years ago still works fine. The major things that won't

In general, I think the web has decent backwards compatibility. With a few exceptions, websites from ten years ago still works fine. The major things that won't work are extensions (NSAPI, Flash, etc) or features that were experimental or obscure at the time. To me this is actually the big problem. I would love to have a reduced feature set (could be opt-in) in the browser environment. As it stands it's just an ever growing ball of mud that ironically inhibits innovation and makes browsers impossible to develop without a huge amount of effort. It feels like 95% of the APIs are not used on 95% of usage sessions.