AudioScrobbler is the technology used by Last.fm to keep track of its users' listening habits. If you have a Last.fm account, then you can keep it up to date by enabling the AudioScrobbler module. Each time you listen a to track, information about it are submitted to Last.fm.
This module does not have a configuration window. When it needs to submit some track information, and it does not know your username and/or your password, then you are prompted for them. See this page for more information.
This module uses a cache on your hard drive to store track information before submitting them to Last.fm, and removes them from the cache only once they have been successfully submitted. This means that: