Why are atlas Prometheus and Pandora called Shepard moons?

Atlas, Prometheus, and Pandora are referred to as "shepherd moons" because they help maintain the structure of Saturn's rings through their gravitational influence. These moons exert tidal forces that can clear gaps in the rings or confine ring material, creating distinct edges or waves. For instance, Atlas confines a ringlet within its orbit, while Prometheus and Pandora help define the boundaries of the F ring. Their interactions with the ring particles illustrate the dynamic relationship between moons and ring systems.