Sometimes latches are inconvenient to use when forming complex memory circuits because the value they store can be changed whenever the input changes. In huge circuits, the exact timing of the wires becomes a monumental headache and occasionally different wires are slower to react than others, due to length of the wire, delay of gates and other reasons.

Latches are said to be level-triggered because changes in their stored values are triggered by changes in the values of their inputs. In particular these input values change from a 1 to a 0, or a 0 to a 1, and stay there for a while. It is only after the inputs have changed to a new value and stayed there that the latches record their new values.