One of the most popular of these services is Bit.ly, not just because of the reduction in the size of the resulting URLs, but also the hits statistics which it offers.
Shortening a web address is as easy as inputting the address in the relevant field and clicking the button marked Shorten. The compressed URL will be instantly displayed.
At the same time, this link will be added to the history of URLs that you have shortened with this service, so that you can retrieve it later.
Another outstanding feature is the possibility of viewing the hits stats for each link, thus enabling you to analyze the impact that the publication of the link has had.
When you create a free account you receive even more options, letting you link your Twitter account and post to it directly from Bit.ly. Additionally, your shortened URLs history is accessible from anywhere so long as you have securely logged into your account.