As I know HSTS is mainly implemented to mitigate famous sslstrip attack in which browser is forced to use ssl when connecting to particular site. And I think it also prevents user to proceed to site if there is a problem with ssl cert which the site provides. Are there anything more to know about HSTS ?
Also I read mostly superficial info about HSTS and that it can be defeated. Is this possible ? (Except the obvious way to intercept before the user connects first time and block hsts header)
Which browsers support hsts ? Can hsts data be cleared like clearing browser history and cookies?