The cup is a rounding-bottom. The handle is a short, shallow drift lower near the right rim, usually on lighter volume, which shakes out traders who bought the recovery. The entry is a break above the handle.
The handle is the useful part. It provides a nearby invalidation-level, which turns a pattern with a vague stop into one with a defined risk, and the shallowness of the handle is treated as evidence that holders are not eager to sell.
Common failure modes are a handle that is too deep, retracing much of the cup, and a breakout on weak volume that drops straight back inside. Both are worth defining numerically in advance rather than judged by eye after the fact.
Related: rounding-bottom, volatility-contraction-pattern, breakout, volume-dry-up, failed-pattern