What occurs in a "trill" in music?

A trill in music is a technique characterized by the rapid alternation of two adjacent tones, typically a note and the note immediately above it. This ornamentation serves to enhance the expressiveness and complexity of a melody. It is often notated with the abbreviation "tr" above the notes and is a common feature in various musical styles, from classical to contemporary.

The rapid movement between the two pitches creates a vibrant and lively effect, drawing the listener's attention and adding emotional intensity to the piece. Trills are frequently used in solo instrumental works and vocal compositions to demonstrate virtuosity and enhance musical phrasing. This unique combination of speed and proximity of the notes distinguishes trills from other musical techniques such as crescendos or accents, which serve different purposes within the musical context.