In music

Music

Music is an art form whose medium is sound and silence. Its common elements are pitch , rhythm , dynamics, and the sonic qualities of timbre and texture...

, the introduction is a passage or section

Section (music)

In music, a section is "a complete, but not independent musical idea". Types of sections include the introduction or intro, exposition, recapitulation, verse, chorus or refrain, conclusion, coda or outro, fadeout, bridge or interlude...

 which opens a movement

Movement (music)

A movement is a self-contained part of a musical composition or musical form. While individual or selected movements from a composition are sometimes performed separately, a performance of the complete work requires all the movements to be performed in succession...

 or a separate piece

Musical composition

Musical composition can refer to an original piece of music, the structure of a musical piece, or the process of creating a new piece of music. People who practice composition are called composers.- Musical compositions :...

. In popular music

Popular music

Popular music belongs to any of a number of musical genres "having wide appeal" and is typically distributed to large audiences through the music industry. It stands in contrast to both art music and traditional music, which are typically disseminated academically or orally to smaller, local...

 this is often abbreviated as intro. The introduction establishes melodic

Melody

A melody , also tune, voice, or line, is a linear succession of musical tones which is perceived as a single entity...

, harmonic

Harmony

In music, harmony is the use of simultaneous pitches , or chords. The study of harmony involves chords and their construction and chord progressions and the principles of connection that govern them. Harmony is often said to refer to the "vertical" aspect of music, as distinguished from melodic...

, and/or rhythm

Rhythm

Rhythm may be generally defined as a "movement marked by the regulated succession of strong and weak elements, or of opposite or different conditions." This general meaning of regular recurrence or pattern in time may be applied to a wide variety of cyclical natural phenomena having a periodicity or...

ic material related to the main body of a piece.

Introductions may be an ostinato

Ostinato

In music, an ostinato is a motif or phrase, which is persistently repeated in the same musical voice. An ostinato is always a succession of equal sounds, wherein each note always has the same weight or stress. The repeating idea may be a rhythmic pattern, part of a tune, or a complete melody in...

 that is used in the following music, an important chord

Chord (music)

A chord in music is any harmonic set of two–three or more notes that is heard as if sounding simultaneously. These need not actually be played together: arpeggios and broken chords may for many practical and theoretical purposes be understood as chords...

 or progression

Chord progression

A chord progression is a series of musical chords, or chord changes that "aims for a definite goal" of establishing a tonality founded on a key, root or tonic chord. In other words, the succession of root relationships...

 that establishes the tonality

Tonality

Tonality is a system of music in which specific hierarchical pitch relationships are based on a key "center", or tonic. The term tonalité originated with Alexandre-Étienne Choron and was borrowed by François-Joseph Fétis in 1840...

 and groove for the following music, important but disguised or out of context motivic

Motif (music)

In music, a motif or motive is a short musical idea, a salient recurring figure, musical fragment or succession of notes that has some special importance in or is characteristic of a composition....

 or thematic

Theme (music)

In music, a theme is the material, usually a recognizable melody, upon which part or all of a composition is based.-Characteristics:A theme may be perceivable as a complete musical expression in itself, separate from the work in which it is found . In contrast to an idea or motif, a theme is...

material (ibid). As such the introduction may be the first statement of primary or other important material, may be related to but different from the primary or other important material, or may bear little relation to any other material.