Definition

Noun: A key signature is a set of sharp (♯) or flat (♭) symbols placed together on a musical staff, immediately after the clef. It indicates the key of a piece of music by specifying which notes are to be consistently raised or lowered throughout the composition, unless otherwise marked by accidentals.

Usage

The key signature is a fundamental element of Western musical notation. It tells the performer the tonal center, or "home" key, of the music (e.g., G major, F minor) and eliminates the need to write accidentals (sharps or flats) next to every single affected note in the score.

Examples

• The key signature with one sharp (F♯) typically indicates the key of G major or E minor.
• Before you start playing, always check the key signature to know which notes are sharp or flat.
• The composer changed the key signature in the middle of the piece to modulate to a new key.
• A piece in the key of C major has no sharps or flats in its key signature.

Advanced Usage

• Reading a Key Signature: The order of sharps is F♯, C♯, G♯, D♯, A♯, E♯, B♯. The order of flats is the reverse: B♭, E♭, A♭, D♭, G♭, C♭, F♭. Memorizing these orders helps in quickly identifying the major key.
• Relative Major/Minor: Every major key signature also corresponds to a relative minor key (which shares the same notes). For example, the key signature for G major (one sharp) is also used for its relative minor, E minor.
• Modulation: A change of key signature within a piece signals a modulation (a shift) to a new key.

Variants and Related Words

• Signature (noun): In a musical context, this can be short for either key signature or time signature. The meaning is determined by the surrounding context.
• Accidental (noun): A temporary sharp (♯), flat (♭), or natural (♮) symbol that alters a note from its pitch as defined by the key signature.
• Clef (noun): A symbol (treble clef, bass clef, etc.) placed at the beginning of the staff to assign note names to the lines and spaces. The key signature always follows the clef.

Synonyms

• Musical signature (less common)
• Tonality indicator (descriptive)

Related Phrases

• To be in a key: To have a specific tonal center, as shown by the key signature.
  • This song is in the key of D major, as you can see from its two-sharp key signature.
• Without a key signature: Refers to music in the key of C major or A minor, which have no sharps or flats.
  • The beginner's exercise is written without a key signature.

Noun

1. the sharps or flats that follow the clef and indicate the key