Nightcore

A nightcore (also known as sped-up song, sped-up version, sped-up remix, or, simply, sped-up^{[1][2][3][4][5][6][7]}) edit is a version of a music track that increases the pitch and speeds up its source material by approximately 35%. This gives an effect almost identical to playing a 33⅓-RPM vinyl record at 45 RPM. This 35% increase in RPM causes the note C₄ to become slightly lower in pitch than the note F#₄ (261.63 Hz becomes 353.19 Hz) which is an increase of approximately 5 and a half semitones.^[8] Playing 33⅓-RPM Vinyl Trance records at 45RPM was common in the Happy Hardcore scene of the 90s and 2000s, which most likely inspired the genre.

The name is derived from the Norwegian musical duo "Nightcore", who released pitch-shifted versions of trance and Eurodance songs. Nightcore is also commonly associated and accompanied with anime and otaku culture, with many YouTube thumbnails of nightcore remixes containing anime characters and art.

During the early 2020s, nightcore, under the name "sped-up", became substantially popular thanks to TikTok, where many sped-up versions of older songs were watched millions of times.^[7][5] In turn, major recording labels saw sped-up versions of popular songs as a relatively cheap opportunity to popularize older songs.^[7][1][6] They either started releasing three versions (normal, sped-up, and slowed) of a track at the same time (for instance Steve Lacy's "Bad Habit")^[7] or started curating popular Spotify playlists for sped-up versions of hit singles released specifically on their label (such as Warner Music Group^[4]).