When I used C++ a few years ago I declared my classes in a file.h, and pointed all of my file.cpp files towards that file.h so I could use the classes in my file.cpp program without having to redeclare the classes.
I just wrote my first series of classes in php but wanted to use those classes in several files. Is there a similar method to seperate the classes from the file.php files? Or do I have to redeclare my classes in every file.php file I want to use them in?