Comment by tgv

There's one, though. The client can tell the server it has a cached version, but that only works (automatically) for GET in browsers. That could have been solved without resorting to those verbs, of course, but it's legacy.

HEAD allows the server to send meta data without the (potentially very large) body. That could have been solved without verb (as if HEAD is a verb in this case!), of course, but it has its uses.