In music, a loop is a repeating section of sound material. Short sections, such as one or two bars of music can be repeated to create ostinato patterns. Longer sections can also be repeated: for example, a player might loop what they play on an entire verse of a song in order to then play along with it, accompanying themselves.

Loops can be created using a wide range of music technologies including turntables, digital samplers, looper pedals, synthesizers, sequencers, drum machines, tape machines, and delay units, and they can be programmed using computer music software. The feature to loop a section of an audio track or video footage is also referred to by electronics vendors as A–B repeat.

Royalty-free loops can be purchased and downloaded for music creation from companies like The Loop Loft, Native Instruments, Splice and Output.

Loops are supplied in either MIDI or Audio file formats such as WAV, REX2, AIFF and MP3. Musicians play loops by triggering the start of the musical sequence by using a MIDI controller such as an Ableton Push or a Native Instruments MASCHINE.

While repetition is used in the music of all cultures, the first musicians to use loops in the sense meant by this article were musique concrete and electroacoustic music pioneers of the 1940s, such as Pierre Schaeffer, Halim El-Dabh, Pierre Henry, Edgard Varèse and Karlheinz Stockhausen. These composers used tape loops on reel-to-reel machines, manipulating pre-recorded sounds to make new works. In turn, El-Dabh's music influenced Frank Zappa's use of tape loops in the mid-1960s.

Terry Riley is a seminal composer and performer of the loop- and ostinato-based music who began using tape loops in 1960. For his 1963 piece Music for The Gift he devised a hardware looper that he named the Time Lag Accumulator, consisting of two tape recorders linked together, which he used to loop and manipulate trumpet player Chet Baker and his band. His 1964 composition In C, an early example of what would later be called minimalism, consists of 53 repeated melodic phrases (loops) performed live by an ensemble. "Poppy Nogood and the Phantom Band", the B-side of his influential 1969 album A Rainbow in Curved Air uses tape loops of his electric organ and soprano saxophone to create electronic music that contains surprises as well as hypnotic repetition. ^{[citation needed]}

Another effective use of tape loops was Jamaican dub music in the 1960s. Dub producer King Tubby used tape loops in his productions while improvising with homemade delay units. Another dub producer, Sylvan Morris, developed a slapback echo effect by using both mechanical and handmade tape loops. These techniques were later adopted by hip hop musicians in the 1970s. Grandmaster Flash's turntablism is an early example in hip hop.^{[citation needed]}

The first commercial drum loop was created for the song "Stayin' Alive" for the movie Saturday Night Fever by Albhy Galuten and Karl Richardson. It was created by recording two measures of drums from the song “Night Fever” and recording them onto a two-track analog tape which was then fed between the capstan and the pinch roller. Because the loop was about 30 feet long, it was fed out to a 7” plastic reel for ballast which was hung over the arm of a microphone stand before the loop of tape returned to the take-up reel. This same loop was later used by the Bee Gees for the song "More than a Woman" also from the Saturday Night Fever soundtrack. That same loop was also use – though slowed down quite a bit, for the Streisand recording of “Woman in Love” produced by Albhy Galuten, Karl Richardson and Barry Gibb. When Jeff Porcaro of the band TOTO came to work with Galuten and Gibb on a Bee Gees record, he was shown the technique of creating drum loops with analog tape. Porcaro subsequently went back to California where he used the method he had learned to create the drum loop that was used by Toto as the foundation of the song Africa.