PHP (engl. «PHP: Hypertext Preprocessor») - popular script programming language that is used to create dynamic web-sites. PHP code is processed on server part using php interpretator, and is not available to other users.
To process php code with interpreter, for files with php scripts should be set read only rights for all users - 644 (default server rights). If any right should be edited by another php script, you will have to set rights for edit - 666. If a script creates files in any folder, the folder also should have rights for server users to write - 777.