A Brief Inquiry into Online Relationships is the third studio album by English band the 1975. It was released on 30 November 2018 by Dirty Hit and Polydor Records. Initially titled Music for Cars, the album was intended as the follow-up to I Like It When You Sleep, for You Are So Beautiful yet So Unaware of It (2016). The term later denoted an era encompassing both their third album and Notes on a Conditional Form, released in 2020. The band halted recording of the first part after lead singer Matty Healy left for a drug rehabilitation clinic in Barbados, seeking treatment for his heroin addiction. Following the singer's return, the band spent several months completing the album in Northamptonshire and Los Angeles.

A maximalist experimental album, A Brief Inquiry into Online Relationships combines rock and pop music with ambient interludes. Eschewing the 1980s-influenced sound of its predecessor, the album embraces a desolate soundscape informed by electronica. Noted for its incorporation of various genres, the record heavily draws from jazz, R&B, electropop, indie rock and Britpop, among others. The songs are characterised by their electronic beats, gospel choirs, neo-soul horns and downtempo rhythms. Guest contributions are featured from the London Community Gospel Choir, No Rome, the Japanese House and Roy Hargrove.

Exploring the role of digital communication and the internet in contemporary life, A Brief Inquiry into Online Relationships is a concept album connected by several overarching threads. The album serves as a cautionary political statement, questioning the implications of society's relationship with technology and its impact on millennials. It marks a shift in Healy's portrayal of heroin addiction, embracing sincerity and honesty to speak on the desolation it causes. Eschewing metaphors and ambiguity, the album utilises black humour, simple lyrics and straightforward storytelling, covering dark topics such as nihilism, suicide, depression, anxiety, dissociation, trauma, cynicism and death, among others.

The album received widespread acclaim from contemporary music critics, who praised the production quality and portrayal of modern life, with some critics calling it a millennial version of Radiohead's OK Computer. It was preceded by the singles "Give Yourself a Try", "Love It If We Made It", "TooTimeTooTimeTooTime", "Sincerity Is Scary" and "It's Not Living (If It's Not with You)". In addition to appearing on numerous publications' year-end and decade-end lists, it won the British Album of the Year at the 2019 Brit Awards. The album became the 1975's third consecutive number one on the UK Albums Chart, and was later certified gold by the British Phonographic Industry (BPI). It also peaked at number four on the US Billboard 200 chart and attained top-ten positions in several countries, including on Ireland, New Zealand and Australia. To further promote the album, the band embarked on their Music for Cars Tour.