Lo-fi hip-hop, or chillhop, is the most-streamed corner of downtempo and the one most people meet first, usually through a livestream of a cartoon student working while the rain comes down.
Strip away the meme and what's left is a genuine lineage: the head-nod boom-bap of J Dilla and Pete Rock, filtered through the jazz-sampling melancholy of Nujabes and his Tokyo label Hydeout Productions, then handed to a generation of bedroom producers with cracked copies of a DAW and an SP-404. The 2004 Samurai Champloo soundtrack did as much as any record to seed the sound.
Drums are soft and swung, sampled from vinyl and left a little behind the beat. Keys and guitars loop four bars at a time, pitched down, drenched in tape hiss and the crackle of a worn record. Nothing builds to a chorus; tracks are two minutes of mood and then a fade.
Because so much of it is functional music, made to recede into the background, the best of it rewards the foreground listen: the sample choice, the off-kilter swing, the small sad chord that turns a study loop into something you actually remember.