Most url shortener convert long webpage address into short URL consisting of a random of letters and numbers.  Other URL shorteners allow you to customize your desired URL in such a way that you retain your keyword for that specific webpage.  By retaining your keywords in your URL, targeted audience are more likely to visit your site and easily remember your webpage address for their future visit and referral to friends.

Among the many benefits of URL shorteners are the following: Affiliate link cloaker.  Using a URL shortener such as allows you to cloak your affiliate ID when promoting them at social sites like Twitter and Facebook.  URL shortener is also beneficial in using Twitter which allows only 140 characters per tweet, thus giving you ample space to briefly describe your webpage.  Another benefit of using URL shortener is convenience in sharing your site to friends at social sites, groups, forums, blogs, SMS, and instant messengers.

Please check out best short urls I found in google search.