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A compilation album is an album (music or spoken-word) featuring tracks from one or more performers, often culled from a variety of sources (such as studio albums, live albums, singles, demos and outtakes.) The tracks are usually collected according to a common characteristic, such as popularity, genre, source or subject matter. When the tracks are all essentially by the same recording artist, a compilation album is often referred to as a retrospective album. Compilation albums may employ traditional product bundling strategies.
Common types 
Common types of compilation include:
- "Greatest hits", "best of", or "singles collection" LPs, gathering together an artist's or a group's best-known songs. If the artist or group continues to record, compilers commonly include one or more previously unreleased tracks as an incentive for fans to buy the album, even if they already have the other material on the compilation.
- Other single-artist compilations, such as rarities or B-side collections, albums compiled from radio sessions, songs performed by an artist exclusively for a film soundtrack or collections that combine multiple releases, such as LPs and EPs together on one or more compact discs. Such compilations generally target existing fans of the artist and have little mainstream appeal, though postmortem compilations of unreleased materials from recently deceased artists have significant popularity.
- Box sets, elaborate multi-disc collections often covering the entire breadth of an artist's career or the full sweep of an entire record label or genre. Many anthologies are released in this format.
- Various artist themed compilations, e.g. love songs, Christmas songs, songs featuring a particular instrument (such as saxophone or piano), and countless other variations.
- Various artist genre compilations, e.g. jazz, synthpop, rock, etc. These may be from the same time period (Year, decade or era, for example), or may incorporate a common theme, as a soundtrack exemplifies well.
- Various artist hit compilations. This has been a very successful part of the album market since the early 1970s. Recent hit singles are gathered together in one place. In the 1970s, these were often single vinyl LPs with 10 to 12 tracks or more. In the 1980s, a double album with 6 or 8 tracks on each side became the norm. Now that CDs are the dominant format, these compilations are usually released on one, two, or three CDs.
- Promotional compilations or Samplers. These are creative, successful forms of promotion for artists and/or record labels to promote their music. Generally, these types of releases are free or cost very little for the consumer or end listener. Elektra Records released the first sampler albums: in the 1950s.
- Private label promotional compilations. Promotional compilation CDs can be private labeled for products, retail outlets, or commercial organizations or non-profit organizations. Artists and labels like to co-brand themselves with well-known brands for marketing purposes, and transversely well-known brands like to co-brand themselves with artists.
- Business-to-business promotional compilations. The music industry may use other types of promotional compilations within a business-to-business context to promote artists to media concerns (radio stations, music supervisors for TV, film or video games for synchronization)
- Composer/producer albums. Many hip-hop and reggaeton producers will release a compilation album which features various artists, but with each track composed by the same producer.
In the United Kingdom, The Official Charts Company compiles a weekly compilation albums chart, limited to Various Artists compilations and soundtrack compilations.
List of notable compilation series 
United States and United Kingdom 
- Mushroom Jazz (Om Records, (1992–present) – genre broken beat/nu jazz/hip-hop
- The Best... Album in the World...Ever! (Virgin Records, 1993–present) – genre & themed (e.g. The Best Christmas...)
- Sessions (Ministry of Sound, 1993–present. Includes Summer Sessions, Chillout Session, Defected Sessions etc. – genre (Dance/electronic)
- Café del Mar (Manifesto, 1994–present) – genre (dance/ambient)
- Jock Jams (Tommy Boy, 1995–~2001) – genre and themed (dance/techno/sports)
- The Annual (Ministry of Sound). 1995–present. The World's best selling dance series. – genre (Dance/electronic)
- DJ-Kicks (!K7, 1995-present)
- Bonkers (Resist Music, 1996–present) – genre (happy hardcore/UK)
- Global Underground (Boxed, 1996–present) – genre (Dance/electronic)
- "WOW", 1996-present – genre (Contemporary Christian music)
- Dance Nation, 1996–present, Ministry of Sound – genre (Dance/electronic)
- Pure Moods (Virgin Records, 1997–2004) – genre (New age)
- EMI Songbook Series (EMI, 1999, spotlight of favorite music of featured artist)
- 20th Century Masters: The Millennium Collection ((Universal Music Group, 1999–present))
- Have a Nice Day (CD series) - 70s music (Rhino Records, 1990–1996, 25 volumes)
- Trance Nation (Ministry of Sound), 1999–present – genre (Dance/electronic)
- In Search Of Sunrise (Songbird), 1999–present – genre (Dance/electronic)
- Clubbers Guide to..., 2000–present, Ministry of Sound – genre (Dance/electronic)
- The Essential (Sony BMG, 2000–present)
- Gold (Universal Music Group, 2005–present)
- Saint-Germain-des-Prés Café, (2001–present) – genre nu jazz/deep house
- Simply the Best..., (Warner Music) – genre & themed (e.g. Simply The Best Movie Album)
- Endzeit Bunkertracks, (Alfa Matrix, 2005–present) – genre Electro-Industrial/Noise/Dark Electro
- Dark Was The Night (4AD, 2009–present) - Contains songs from many independent artists. A part of the AIDS Benefit Series.
- Essential R&B (Sony BMG, 2004–present)
- Housexy (Ministry of Sound), 2005–present – genre (Dance/electronic)
- Fabriclive (Fabric, 2000–present)
- Punk Goes... (Fearless Records, 2000–present) - genre pop/punk/metal
See also