Last.fm is an internet radio and music community site founded in 2002 in the UK that allows users to listen to free music streaming radio based on their music tastes. Users can create a personalized radio station by entering an artist and Last.fm will generate a playlist of similar music based on the tastes of other users. It offers features like custom profiles, adding friends to find new music through their tastes, and tracking the music you listen to. Last.fm hosts a wide variety genres and popular artists but does have some limitations like not having every song available and requiring personal information to purchase music.