Tremolo

What it is: Rapidly alternating the bow back and forth on a single note (or between two notes).

Two types: Unmeasured tremolo (notated with slashes through the stem) — as fast as possible, creating a blur. Measured tremolo — rhythmically precise alternation, usually in sixteenths or thirty-seconds.

What it sounds like: Tension, suspense, shimmer. Unmeasured tremolo is the classic "something is about to happen" texture. Measured tremolo has more rhythmic drive.

When to use it: Building suspense, creating background energy, storm scenes, transitions.

Tip: Tremolo in the lower strings (violas, cellos) is darker and more ominous. In violins, it's brighter and more agitated.