mod_rewrite

mod_rewrite is Apache module that is used for rewriting a URL at the server level.

mod_rewrite provides a flexible and powerful way to manipulate URLs using an unlimited number of rules.

It provides a way to modify incoming URL requests dinamically.

A rewrite rule can be invoked in httpd.conf or in .htaccess.

The URL manipulations can depend on various tests: server variables, environment variables, HTTP headers, time stamps, external database lookups, and various other external programs or handlers, and can be used to achieve granular URL matching.

The following link provides detailed mod_rewrite documentation.