config,common,function,webmailer

[vijukumar]

why we use these files in php? please tell me why they have been used and how they work?

[Auzzie]

the way in which those files work depends on what code you put inside of them.

They dont do specific jobs, they are just useful names to help you remember what is in them, for example:
common.php usually contains any piece of code that you would commonly call like session_start() or anything of the sort.

config.php is usually named that way because people usually store their configuration details in there.

Hope this has cleared it up a little

[forzadraco]

it just aname..it's depending what you write in your code..
example: config.inc.php, its usually webmaster store their web configuration

A function is a block of code that can be executed whenever we need it.

[vijukumar]

will any body pass me the default config.php codes and database.class? so that i can alter as i require.

[nav33n]

There is NO default config.php and database.class in php. :)