The chown() function is quite rarely used in PHP as you require special privileges to change the ownership of a file, and only crazy people run their web server with any privileges beyond reading the public HTML directory. However, on the command-line chown() is helpful now and then, and it attempts to change the file passed in parameter one so that it is owned by the user specified in parameter two. On success, true is returned, otherwise false. The second parameter can either be a username or a user ID number.
Note that chown() only works on local filesystems.