Dream pop is a subgenre of alternative rock and neo-psychedelia that emphasizes atmosphere and sonic texture as strongly as it does pop melody. Common characteristics include breathy vocals, dense productions, and effects such as reverb, echo, tremolo, and chorus. It often overlaps with the related genre of shoegaze, and the two genre terms have at times been used interchangeably.

Dream pop came into prominence in the 1980s through groups associated with the UK label 4AD, most prominently Cocteau Twins and This Mortal Coil, and later A.R. Kane, who are credited with coining the term. During the late 1980s to early 1990s, the genre saw further proliferation through UK-based artists such as My Bloody Valentine, Slowdive, and Lush alongside US-based acts Galaxie 500, Julee Cruise, and Mazzy Star. By the late 2000s, the sound saw renewed popularity among millennial listeners through bands such as Beach House.

The term "dreampop" was originally coined by Alex Ayuli of A.R. Kane to describe the duo's sound in the late 1980s. The term is thought to relate to the listener's "immersion" in the music. The AllMusic Guide to Electronica defines dream pop as "an atmospheric subgenre of alternative rock that relies on sonic textures as much as melody". According to Paste, the genre emphasizes mood and sonics over lyrics, so that "chords and tracks blur seamlessly into one another so frequently that it can be difficult to even decipher when one song ended and another has begun." Common characteristics are breathy vocals, guitar effects, and a densely produced sound, with "nebulous, distorted guitars" paired with "murmured vocals sometimes completely smudged into a wall of noise." The music tends to focus on textures rather than propulsive rock riffs. Effects such as reverb and echo are ubiquitous, with tremolo and chorus also heard on recordings to achieve the style's "floaty, surreal, cloud-like haze".

Dream pop is a distinct genre from shoegaze, although the terms have sometimes been used interchangeably. The style also overlaps with indie rock, indie pop and synth pop. According to Pitchfork, the term "was always more of a descriptor than a proper genre" and its defining features are "atmosphere, intimacy, a light coating of psychedelia, and, yes, dreaminess."

Lyrics are often introspective or existential in nature, but may be difficult to hear or incomprehensible in the mix. Critic Simon Reynolds wrote that dream pop "celebrates rapturous and transcendent experiences, often using druggy and mystical imagery". In 1991, he suggested this escapist tendency might be a response to the cultural landscape of the UK during the 1980s: "After 12 years of Conservative government in Britain, any idealism or constructive political involvement seems futile to these alienated middle-class dropouts." Similarly, according to Rachel Felder, dream pop artists often resist representations of social reality in favour of ambiguous or hallucinogenic experiences. According to Paste, "Dream pop artists aren't poets—they're painters patching together swaths of sound into a big, beautiful landscape."

Author Nathan Wiseman-Trowse writes that the "approach to the sheer physicality of sound" integral to dream pop was "arguably pioneered in popular music by figures such as Phil Spector and (Beach Boys founder) Brian Wilson." The Beach Boys recorded an early dream pop song, "All I Wanna Do", for their 1970 album Sunflower. Critic Jim Allen, who cites the Beach Boys as the style's "godfathers", says the song's unprecedented "cinematic dream sequence" production style marks the point "where the dream pop family tree starts to come into focus." The Beach Boys' impact on the genre was not widely acknowledged until the 2000s.

The 1960s work of the Byrds influenced the "swoony harmonies" of later British dream pop groups. The music of the Velvet Underground in the 1960s and 1970s, which experiments with repetition, tone and texture over conventional song structure, is also an important touchstone in the genre's development. The Velvet Underground & Nico (1967) incorporates what music critic Marc Beamount terms "psychedelic dream pop" in addition to various other styles. Elements of dream pop are also found in Velvet Underground songs such as "Candy Says" (1969).

Music journalist John Bergstrom recognises George Harrison's 1970 track "Let It Down" as a progenitor of the genre, and has said its Spector-produced parent album All Things Must Pass influenced "many guitar-driven, echo-drenched bands [that] have come around since, mixing powerful rave-ups with moody, reflective down-tempo numbers and a spiritual bent".