1. Shorten your URL to make it easier to read and retype.
2. Customize your URL so it will make sense to your viewers (for example, three lines of a long URL for a Teen Writing Competition can be shortened to http://bit.ly/TWC2014).
3. Gather statistics on how many times they were clicked, where patrons found the URL (from email to Facebook to newspaper websites), and what time of day they are being accessed.
Why use this for you library?
1. It is perfect for fliers. No one wants to type in a long URL and it fits much better if you're putting the URL on a pull tab flier. I've used it for event registration to writing contest submission links.
2. It is easier to read in email and you don't have to worry about sending broken links.
3. It's click tracking information is useful for targeting your marketing efforts.
4. It is easy to remember. I made a short URL for our page test, which made it easy to bookmark the test to all 10 of our laptops. I also made resource guides on my Google Documents account, so when I want to add more information, I just have to type in the quick URL to access it (handy when you share multiple computers with your coworkers).
5. It looks professional. If you want to upgrade to a paid service, you can customize the whole URL to only reflect your name. But even if you use the shortener's domain, it just looks clean and organized to see a URL that makes sense instead of a URL that is three lines long of gibberish.
It is very easy to use. Check out a screenshot of Bitly (Click on image to enlarge):