GET, POST, and HEAD are the only ones used because since time immemorial, they've been the only ones implemented by the browsers (NN, IE, FF, etc.). I posit th

GET, POST, and HEAD are the only ones used because since time immemorial, they've been the only ones implemented by the browsers (NN, IE, FF, etc.). I posit that if Netscape had implemented PUT, we'd all be talking about the four main verbs, instead of the three main verbs.