Thread: EOF Explanation Anybody?

Hello,
I don't quite understand the constant, EOF. In php I work with opening and reading external(non-program) files such as csv or txt, and I use EOF as end of that file.

Does EOF in C mean EOF of the program, and if so, is this like reading the file from top to bottom? I have a small program that basically goes into loop waiting for user input and it tests :

Code:

while(something != EOF){

Blah blah

}

Anybody shed some light?
Im new to C by the way.