Introduction (Intro)

An introduction comes before the main business of a piece. It can be a few bars of accompaniment that establish the beat before the singer enters, or a long, slow passage that opens a symphony. Either way, its job is to prepare the listener, and the performers, for what follows.

Intros in songs

In popular music the intro usually:

• sets the tempo and groove so the band and singer lock in together,
• establishes the key, often by playing the chords of the verse or chorus,
• introduces a riff or hook that will come back later.

Typical intros last four or eight bars. Some songs skip the intro entirely and start straight on the vocal, sometimes called a cold open. A short repeated chord pattern that can loop until the singer is ready is called a vamp.

Intros in jazz

Jazz musicians often make up intros on the spot. Common choices are a four- or eight-bar turnaround (for example the chords I–vi–ii–V repeated), the last bars of the tune played as a lead-in, or a piano or bass ostinato that becomes the accompaniment.

The slow introduction

In Classical and Romantic symphonies, a fast first movement in sonata form sometimes begins with a slow introduction. It often moves through unstable harmonies and ends on the dominant, creating suspense before the fast music begins. Many of Haydn's later symphonies open this way, as do Beethoven's Symphonies No. 1 and No. 7.

Introduction or prelude?

An introduction belongs to the movement it opens and cannot stand alone. A prelude is a complete piece, even if it was originally meant to come before another one, and an overture is a complete orchestral piece that opens an opera, play or concert.

Intros in teaching pieces

Many easy piano pieces and rags begin with a short introduction. Joplin's "The Entertainer" opens with a four-bar introduction that slides down the keyboard before the first strain begins. The Inside The Entertainer study shows it.