TinyURL shortens long URLs by assigning them to an alias appended to the TinyURL.com domain name. For example, a user may use TinyURL to shorten a long URL such as http://www.this-is-a-very-long.com/hypothetical-URL/that-would-break-in-an-email/and-doesn't-look-very-good/in-text and turn it into a shorter link similar to http://www.tinyurl.com/shrtrvrsn.
Unless a user specifies a custom alias when creating a TinyURL link, the service automatically generates an alias composed of different numbers and letters to help simplify the URL creation process. However, in certain cases, such as to encourage brand recognition in links used in promotions and marketing work, users can specify custom aliases that take the place of automatically generated aliases appended to the TinyURL.com domain name. The service limits the character set used in custom aliases to letters, numbers and dashes.
TinyURL does not store copies of actual Web pages. Instead, it works by redirecting users to the original URL when a TinyURL link is accessed. It does this by passing a special status code to the user's browser telling it that the content that should have been there was permanently moved to a different address. The user's browser then jumps to this address and displays the proper Web page.
Links created using the TinyURL service never expire; however, this doesn't mean a page connected to a TinyURL link becomes accessible forever. Because TinyURL only redirects traffic to the address provided when a link is created, when the original page becomes inaccessible, the TinyURL link breaks too. When an inaccessible page is restored, the TinyURL link starts working again.