Last.fm

Last.fm is a music website, founded in the United Kingdom in 2002. It has claimed over 40 million active users based in more than 190 countries. On 30 May 2007, CBS Interactive acquired Last.fm for UK£140m (US$280m).

Using a music recommender system called "Audioscrobbler", Last.fm builds a detailed profile of each user's musical taste by recording details of the songs the user listens to, either from Internet radio stations, or the user's computer or many portable music devices. This information is transferred to Last.fm's database ("scrobbled") either via the music player itself (Rdio, Spotify, Amarok) or via a plugin installed into the user's music player. The profile data is then displayed on the user's profile page. By April 2011 Last.fm reported more than 50 billion scrobbles. 

The service is free, however users living outside the UK, US, and Germany, require a subscription to use the radio service (€3.00 per month after a 30 track free trial). The site offers numerous social networking features and can recommend and play artists similar to the user's favourites.

Charts

One particular feature of Last.fm is the automatic weekly generation and archiving of detailed personal music charts and statistics which are created as part of its profile building. Users have several different charts available, including Top Artists, Top Tracks, and Top Albums, as well as Weekly Top Artists and Weekly Top Tracks. Each of these charts is based on the actual number of people listening to the track, album or artist recorded either through an Audioscrobbler plugin or the Last.fm radio stream.

Additionally, charts are available for the top tracks by each artist in the Last.fm system as well as the top tracks for individual albums (when the tagging information of the audio file is available). Artist profiles also keep track of a short list of Top Fans, which is calculated by a formula meant to portray the importance of an artist in a fan's own profile, balancing out users who play hundreds of tracks overall versus those who play only a few.

As the information generated is largely compiled from the ID3 data from audio files "scrobbled" from user's own computers, and which may be incorrect or misspelled, there are many errors in the listings. Tracks with ambiguous punctuation are especially prone to separate listings, which can dilute the apparent popularity of a track. Artists or bands with the same name are not always differentiated. The system attempts to translate some different artist tags to a single artist profile, and has recently attempted to harmonise track names.

Charts are also available for user groups, thus providing a view into a demographic slice, and can reveal interesting new music based on the preferences of similar users.

Global charts

Last.fm generates weekly "global" charts of the top 400 artists and tracks listened to by all Last.fm users. To prevent the artificial boosting of an artist or song by deliberately repeated tracks from a single listener, these charts are based on the total number of individual listeners (the reach) and not the number of actual plays.

The result is notably different from traditional commercial music charts provided by the UK Top 40, Billboard magazine, Soundscan and others, which are based on radio plays or sales. Last.fm charts are less volatile and a new album's release may be reflected in play data for many months or years after it drops out of commercial charts. For example, The Beatles have consistently been a top 5 band at Last.fm, reflecting the continued popularity of the band's music irrespective of current album sales. Significant events, such as the release of a highly anticipated album or the death of an artist can have a large impact on the charts.

The Global Tag Chart shows the 100 most popular tags that have been used to describe artists, albums, and tracks. This is based on the total number of times the tag has been applied by Last.fm users since the tagging system was first introduced and does not necessarily reflect the number of users currently listening to any of the related "global tag radio" stations.

Radio stations

Last.fm offers customized virtual "radio stations" consisting of uninterrupted audio streams of individual tracks selected from the music files in the music library.

Stations can be based on the user's personal profile, the user's "musical neighbors", or the user's "friends". Groups based around common interests or geography also have radio stations if there are enough members, and tags also have radio stations if enough music has the same tag. Radio stations can also be created on the fly, and each artist page allows selection of a "similar artists" or "artist fan" radio station. As of May 2009, Last.fm introduced Visual Radio, an improved version of last.fm radio. This brought features such as an artist slideshow and combo stations, which allows for listening to stations consisting of common similar artists of up to either 3 artists or 3 tags.

Under the terms of the station's "radio" license, listeners may not select specific tracks (except as previews), or choose the order in which they are played, although any of the tracks played may be skipped or banned completely. The appropriate royalties are paid to the copyright holders of all streamed audio tracks according to the law in the UK. The radio stream uses an MP3 stream encoded at 128 kbit/s 44.1 kHz, which may be played using the in-page flash player or the downloaded Last.fm client, but other community-supported players are available as well as a proxy which allows using a media player of choice.

On 24 March 2009, Last.fm announced that Last.fm Radio will require a subscription of €3.00 per month for users living outside the US, the UK and Germany. This change was to take effect on March 30, but was postponed until April 22. The decision resulted in over 1000 comments, most of them negative, on the last.fm blog.