Vespertine is the fourth studio album by Icelandic recording artist Björk. It was released on 27 August 2001 in the United Kingdom by One Little Independent Records and in the United States by Elektra Entertainment. Production on the album began during the filming of Dancer in the Dark. With Vespertine, Björk aspired to create an album with an intimate and domestic feeling, deviating from the brash sonority of her previous studio album Homogenic (1997).

The musical style of the album reflected Björk's newly found interest in the minimal and intricate electronic music of producers such as Opiate, Console and the duo Matmos, who were all enlisted for the album. With the rising popularity of Napster and music downloads, she also composed arrangements with thin, "icy" sounding instruments whose quality would not be compromised when downloaded and played on a computer, including the harp, the celesta, clavichord, strings and custom music boxes. Assisted by Matmos, Björk created "microbeats" from various commonplace sounds, such as that of shuffling cards and ice being cracked. Lyrically, the album revolves around sex and love—sometimes explicitly—inspired by her at the time new relationship with Matthew Barney; other lyrical sources include the poetry of E. E. Cummings and British playwright Sarah Kane's Crave.

Vespertine peaked at number 19 on the US Billboard 200 and at number 8 on the UK Albums Chart. It was widely acclaimed by critics, with praise centred on its erotic, intimate mood and sonic experimentation. The album appeared on several publications' lists of the best albums of 2001 and of the decade, and has often been considered Björk's best album to date. It was certified gold in Canada, France, and the United Kingdom. Three singles were released from Vespertine: "Hidden Place", "Pagan Poetry", and "Cocoon". In 2001, she enlisted Zeena Parkins, Matmos, and a choir of Inuit women to embark on the Vespertine World Tour, which took place at theatres and small venues, in favor of acoustics over audience numbers. Björk, a self-titled coffee table book containing photographs of the artist throughout her career, was released simultaneously with the album.