What does Key mean in music?

Key

The tonal centre that organises a piece of music around a specific note and scale.

About Key

A key defines the harmonic and melodic framework of a compositionCompositionThe art and craft of creating original music by organising sounds, rhythms, and harmonies into a…View full entry → by establishing a tonicTonicThe first and most important note of a key, serving as the central point of rest and resolution.View full entry → note and a corresponding scaleScaleAn ordered series of pitches ascending or descending by step.View full entry → — either major or minor. When a piece is said to be "in the key of C major," it means the note C functions as the gravitational centre, and the pitches used are predominantly those of the C major scaleMajor ScaleA seven-note scale with the pattern tone–tone–semitone–tone–tone–tone–semitoneView full entry →.