When do you use POST and when do you use GET?
I read from a book that POST is used to send data to the server that somehow causes a change in the state of the server, such as inserting data in a database. And GET is used for data retrieval that doesn't change anything on the server.
I actually don't quite understand the above. Can someone demostrate it with an example? The example would show that if I replace $_POST by $_GET, the code wouldn't work.
Am I right to say that we can do without GET but we can't do without POST?