Bit.ly is a simple url shortening service that takes your long page URL and makes it much shorter. This data-type makes the process easy to use with in Umbraco.
When you install this package, it will create a new data-type called "Bit.ly Url Shortener", as a default it will contain the API credentials for the "bitlyapidemo" user. Please feel free to change these to your own.
Next you need to add the new data-type to your document type and the rest should be straight-forward.
It is important to note that this data-type does NOT automatically generate a short Bit.ly URL, it must be generated as required. The reasoning behind this is to allow for more control and selection with which pages/URLs are shortened.