Hi, Thanks for your explaination but i still dont understand completly. I can write some function (without class definition) and put in a file then call require() to include that file in other file to use it. With class definition, i HAVE to do the same thing except that i HAVE to instantiate the class which has been included before i can use it! So what 's the point of using object oriented programming in web programming? Extra work, the same functionality and same data need to be sent over network(assumming apache server is on a different machine than the php files, thus, in order to process a completed php file, apache must fetch the class file and the main php file which uses the class!) Hope anyone can clearify my concern Thanks in advance