A globular cluster is a spherical collection of stars which consists of ten thousand to one million stars. Orbiting a galactic core as a satellite, globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. They populate the halo of the Milky Way and other galaxies with a significant concentration toward the Galactic Center. The name of this category of globular cluster is derived from the Latin globulus—a small sphere.
Our galaxy has about 200 globular clusters, most in highly eccentric orbits that take them far outside the Milky Way. Most other galaxies have globular cluster systems as well, in some cases, such as the M87, containing several thousands of globulars.