A count off, count in, or lead-in is a verbal, instrumental or visual cue used in musical performances and recordings to ensure a uniform entrance to the performance by the musicians and to establish the piece's initial tempo, time signature and style. Although a count off usually lasts just one or two bars, it is able to convey the music's style, tempo, dynamics from the leader (such as the conductor, bandleader or principal) to the other performers. A count off is generally in the same style of the piece of music—for instance, a joyful swing tune should have an energized count off. A misleading lead-in, one which indicates a different meter than that of the piece, is a false trail. Counting off is evident in musical genres other than Western classical and popular music; Ghanaian ethnomusicologist J. H. Kwabena Nketia has observed the benefits of such techniques in West African music.
In recorded music, the final two beats of the count off (one, two, one—two—three—four) are often silent to avoid spill onto the recording, especially if the piece has a pickup. The count off is typically edited out after the recording has finished. There are, however, instances where the count off is deliberately kept on a recording—sometimes even edited onto a recording. In the case of "I Saw Her Standing There" by The Beatles, the count off was edited onto a different take of the song. A recorded count off can be made by musicians through an open microphone or through the studio's talkback system, the latter being done by non-performing personnel such as the producer or engineer. The inclusion of a count off in a studio recording may give the impression of a live performance, as on the Beatles' "Sergeant Pepper's Lonely Hearts Club Band Reprise" (1967).
- "Let's Dance" by Chris Montez (1962)
- The song's verses accent upbeats on beats 1 and 3 and vice versa for the rest of the song, so drummer Jesse Sailes counts it off as "one—two—one, two, three".
- "I Saw Her Standing There" by The Beatles (1963)
- "Wooly Bully" by Sam the Sham and the Pharaohs (1965)
- The song features a bilingual count off of "uno, dos, one, two, tres, cuatro".
- "Taxman" by The Beatles (1966)
- "A Day in the Life" by The Beatles (1966)
- "Give Peace a Chance" by John Lennon and the Plastic Ono Band (1969)
- "Get Up (I Feel Like Being a) Sex Machine" by James Brown (1970)
- The song begins with a few seconds of spoken dialogue, which Brown ends by saying "can I count it off? One—two—three—four!"
- "I Don't Wanna Face It" by John Lennon (1984)
- "Patience" by Guns N' Roses (1988)
- The song begins as bass guitarist Duff McKagen gives out the count off. "One, two, one, two, three, four".
- "You Get What You Give" by the New Radicals (1998)
- "You'll Never Meet God (If You Break My Heart)" by Carly Hennessey (2001)
- Co-written by the New Radicals' Gregg Alexander, the song echoes his introduction to 1998's "You Get What You Give" with a count off of "one, two, one–two–three–OW!"
- "Vertigo" by U2 (2004)
- Dunscomb, J. Richard; Willie L. Hill (2002). Jazz pedagogy : the jazz educator's handbook and resource guide. Van Nuys, CA: Alfred Publishing Co. p. 63. ISBN 0-7579-9125-4.
- "Count off (Count in)". Sweetwater. Retrieved 12 February 2013.
- Dunscomb, J. Richard; Willie L. Hill (2002). Jazz pedagogy : the jazz educator's handbook and resource guide. Van Nuys, CA: Alfred Publishing Co. p. 157. ISBN 0-7579-9125-4.
- Vradenburg, written by Wilbur M. Savidge, Randy Lee (2001). Everything about playing blues (1st ed.). Springtown: Praxis. p. 40. ISBN 1-884848-09-5.
- Weir, Michele (2005). Jazz singer's handbook : (the artistry and mastery of singing jazz; includes jazz standards recorded by Chet Baker ...). Van Nuys, CA: Alfred Publishing Co. p. 76. ISBN 0-7390-3387-5.
- Shepherd, John (ed.) (2003). "Lead-in", Continuum Encyclopedia of Popular Music of the World: Part 1 Performance and Production, p.610. ISBN 978-0-8264-6322-7.
- Van Der Merwe (1989), p.157. Cited in Shepherd (2003).
- London, Justin (2004). Hearing in time psychological aspects of musical meter. Oxford: Oxford University Press. p. 53. ISBN 0-19-803645-0.
- Tedesco, Tommy (2008). For Guitar Players Only. Van Nuys, CA: Alfred Publishing Co. p. 84. ISBN 1-4574-3052-5.
- Sharp, J.D. (1992). Home recording techniques : a step-by-step guide to multitracking and mixing. Van Nuys, CA: Alfred Publishing Co. p. 29. ISBN 0-88284-495-4.
- Everett, Walter (2009). The foundations of rock from "Blue suede shoes" to "Suite : Judy blue eyes". Oxford: Oxford University Press. p. 353. ISBN 0-19-971870-9.
- Lewisohn, Mark (1988). The Beatles recording sessions (1st ed.). New York: Harmony Books. p. 9. ISBN 0-517-57066-1.
- Hurtig, Brent (1988). Multi-Track Recording for Musicians. Van Nuys, CA: Alfred Publishing Co. p. 90. ISBN 1-4574-2484-3.
- Millward, Simon (2007). Fast Guide to Cubase 4. Tonbridge: PC Publishing. p. 47. ISBN 1-906005-00-1.
- Barrett, Don (2009). Digital Performer 6 power! : the comprehensive guide (Guide (Instructor's) ed.). Boston, MA: Course Technology Cengage Learning. p. 115. ISBN 1-59863-907-2.
- Everett, Walter (2001). The Beatles as musicians the Quarry Men through Rubber soul. New York: Oxford University Press. p. 34. ISBN 0-19-534972-5.
- Scott, Richard J. (2003). Chord progressions for songwriters. New York: Writers Club Press. p. 292. ISBN 0-595-26384-4.
- Everett, Walter (1999). The Beatles As Musicians:Revolver through the Anthology. Oxford: Oxford University Press. p. 34. ISBN 0-19-988093-X.
- Cross, Craig (2004). Beatles-discography.com : day-by-day, song-by-song, record-by-record. New York: iUniverse. p. 271. ISBN 0-595-31487-2.
- Marinucci, Steve. "'The Making of Sgt. Pepper' paved the way for 'Beatles Anthology'". Examiner. Retrieved 12 February 2013.
- Bardola, Nicola (2010). John Lennon : Wendepunkte (1. Aufl. ed.). Zürich: Römerhof-Verlag. p. 160. ISBN 3-905894-07-6.
- Urish, Ben; Bielen, Ken (2007). The words and music of John Lennon (1st publ. ed.). Westport, Conn. [u.a.]: Praeger. p. 88. ISBN 0-275-99180-6.
- Collar, Matt. "Carly Hennessy—Ultimate High". All Music. Retrieved 14 September 2014.
- Calhoun, Scott (2011). Exploring U2 : is this rock 'n' roll? : essays on the music, work, and influence of U2. Lanham, Md.: Scarecrow Press. p. 225. ISBN 0-8108-8157-8.
- Díaz, Itxu (2005). Haciendo Amigos. Ediciones DaylNet. p. 84. ISBN 84-611-1498-1.
- Kootnikoff, David (2012). Bono : a biography. Santa Barbara, Calif.: Greenwood. p. 140. ISBN 0-313-35509-6.