Bitly is a URL shortening service that allows users to quickly and easily shorten long URLs into shorter, more manageable links. With Bitly, users can share links on social media, track link performance, and customize their links with branded domains. Bitly also provides advanced analytics to help users
From Wikipedia
Bitly is a URL shortening service and a link management platform. The company Bitly, Inc. was established in 2008. It is privately held and based in New York City. Bitly shortens 600 million links per month, for use in social networking, SMS, and email. Bitly makes money by charging for access to aggregate data created as a result of many people using the shortened URLs.