When using the microblogging site Twitter, each tweet you send is only allowed to be a maximum of characters. Often you will want to send text along with your link. Many times you will be linking to a page that has a long url and sometimes the link alone will be longer than the allowed 140 characters. Therefore, you must find a way to shorten you link in order to allow for the link to be included with a short description and hashtags.
Twitter Link Shorteners
There are multiple sites that provide link shortening services. You can view a large compiled link shortener list over at searchengineland.com. I prefer to use Bit.ly as my preferred link shortener. It is rather easy to use. Just copy and paste the link into the main box and it will shorten your link down to less than 14 characters. You can also use this same page to track the clicks of any links shortened with Bit.ly. Be sure to check it out, if you are in search of a link shortening service.