Leading tone

In this example, the leading tone of C major (B) resolves to the tonic (C) in a perfect authentic cadence.

In music theory, a leading tone (also called subsemitone or leading note in the UK) is a note or pitch which resolves or "leads" to a note one semitone higher or lower, being a lower and upper leading tone, respectively. Typically, the leading tone refers to the seventh scale degree of a major scale (), a major seventh above the tonic. In the movable do solfège system, the leading tone is sung as si.

A leading-tone triad is a triad built on the seventh scale degree in a major key (vii^o in Roman numeral analysis), while a leading-tone seventh chord is a seventh chord built on the seventh scale degree (vii^ø7). Walter Piston considers and notates vii^o as V⁰
₇, an incomplete dominant seventh chord.^[1] (For the Roman numeral notation of these chords, see Roman numeral analysis.)