A satellite constellation is a group of artificial satellites working together as a system. Unlike a single satellite, a constellation can provide permanent global or near-global coverage, such that at any time everywhere on Earth at least one satellite is visible. Satellites are typically placed in sets of complementary orbital planes and connect to globally distributed ground stations. They may also use inter-satellite communication.
Satellite constellations should not be confused with satellite clusters, which are groups of satellites moving very close together in almost identical orbits (see satellite formation flying), satellite programs (such as Landsat), which are generations of satellites launched in succession, and satellite fleets, which are groups of satellites from the same manufacturer or operator that function independently from each other (not as a system).