Legato

What it is: Smooth, connected bow strokes with no audible break between notes. The bow stays on the string and continues moving through the entire phrase under a single slur.

What it sounds like: A continuous, singing line — like a vocalist sustaining a melody on a single breath. The defining sound of expressive string writing.

When to use it: Lyrical passages, melodic singing lines, anywhere you want a vocal quality. The default for slow movements and singing themes. Any line marked with a slur is at minimum implied legato.

Tip: Legato has a length limit. A bow can travel only so far before it has to change direction. Mark slurs to indicate phrasing; let the player figure out where to change bow within them. A single down-bow at moderate dynamic lasts ~6–8 seconds — plan accordingly.

Listen: Barber, Adagio for Strings — the entire piece is a study in extended legato, with the bow essentially never leaving the string.