URL shortening is a technique to convert a long URL (site or page address) to a shorter version.
This shorter version of the URL is usually cleaner and easier to share or remember. When someone accesses the
shortened address, the browser redirects to the original (large) url address. It is also called URL redirection or URL redirect.
For example, the large version of this url: http://en.wikipedia.org/wiki/URL_shortening
Can be shortened with sir.bz service to this small address, that redirects to the previous longer address: