It means that the wrong type of request was sent for the thing you are requesting
from the server. Each object, such as a web page or a script, can accept certain types
of requests. Browsers usually use the "POST" request when submitting form data, and
the "GET" request at all other times. Most of the time, the error is caused by an incorrect
HTML form.
For example, you can use the "POST" method of submitting forms to a PHP script, but it is
not allowed to be used if the form submits to a normal HTML page because such files are
not capable of processing the data format.
