People typically refer to groups of stars in a pattern as constellations, but the accurate term is asterism; scientists refer to actual groups of stars as clusters and group individual stars by light magnitude. Because constellations are the standard observation grouping, astronomers refer to constellations when naming stars.
Star clusters are categorized into two groups: globular and open, depending on the age of the cluster and number of stars present. One star cluster of note is the Pleiades, also know as the Seven Sisters. This group of stars contains hundreds of stars, but only seven are readily visible to the human eye. The Pleiades cluster is located in the constellation Taurus, and its stars are roughly 425 light years from Earth.