Trills are musical ornaments. A trill sign indicates rapid alternation of a given note with the second above it. How trills are executed depends on the time period the piece was written; trills were performed differently from one musical period (e.g. the Baroque) to the next.
Abbreviation
Size
Slightly less than 2 spaces high.
Placement:
Over the note to be trilled.
Trills are always placed above the staff, no matter what the stem direction of the notes are.
When a trill extends over several notes, the abbreviation goes over the first note to be trilled and then a wavy line, the same type that is used for glissandos, extends over the rest of the notes to be trilled. The wavy line ends above the last note, not the end of its duration.