POST and GET are two HTTP request methods. GET is usually intended to retrieve some data, and is expected to be idempotent (repeating the query does not have any side-effects) and can only send limited amounts of parameter data to the server. GET requests are often cached by default by some browsers if you are not careful.
POST is intended for changing the server state. It carries more data, and repeating the query is allowed (and often expected) to have side-effects such as creating two messages instead of one.
