htaccess files are optional configuration files used in Apache web servers that can be used to control the directories they are placed in and also the sub directories.

If your host allows .htaccess files, you may want to read the below articles and use the powerful techniques explained.

http://perishablepress.com/press/2006/01/10/stupid-htaccess-tricks/

http://www.askapache.com/htaccess/apache-htaccess.html

Try searching for .htaccess and there are tons of articles you will come across.

Believe me, you will be surprised at the numerous tricks that can be done using .htaccess files.