List out the predefined classes in PHP?

Classes are not like predefined functions-there are quite a lot of functions, a class is similar to creating your own function - on a very basic level please do not swamp me with lists of the differences between a class and a function I already know! -

anyway, anything predefined within php will be available to view in the PHP manual - downloadable from the php website and is part of the php package.

but to save you a bit of time here are a list of pre-defined classes (or rather resevered Words that are classes):

http://php.net/manual/en/reserved.classes.php