Tonarten

Tonarten, or keys, are a principle of organizing pitch material around a central pitch called the tonic. Each tonality centers a scale on a tonic and is associated with a specific key signature that indicates which notes are sharpened or flattened in normal notation. In Western music, the two most common kinds are major keys and minor keys; each major key has a relative minor key that shares the same key signature.

The major scale pattern is whole step, whole step, half, whole, whole, whole, half. The natural minor scale pattern is whole, half, whole, whole, half, whole, whole. The key signature reduces the number of accidentals needed in notation.

The circle of fifths is a diagram that arranges keys by adding sharps or flats in a clockwise or counterclockwise order. It aids in understanding key relationships, modulation between keys, and transposition.

Tonarten provide tonal centers for melodies and harmonies. A piece in C major typically centers on C and uses a I–IV–V–I progression; its relative minor, A minor, shares a key signature and similar harmony.

Enharmonic equivalence means some keys sound the same in equal temperament (for example, C# major and Db major) but are used differently in practice for readability or instrument design. The system is grounded in equal temperament tuning, which standardizes pitch distances across the octave.