Jeans instability in the context of Gravitational collapse

Star formation is the process by which dense regions within molecular clouds in interstellar space—sometimes referred to as "stellar nurseries" or "star-forming regions"—collapse and form stars. As a branch of astronomy, star formation includes the study of the interstellar medium (ISM) and giant molecular clouds (GMC) as precursors to the star formation process, and the study of protostars and young stellar objects as its immediate products. It is closely related to planet formation, another branch of astronomy. Star formation theory, as well as accounting for the formation of a single star, must also account for the statistics of binary stars and the initial mass function. Most stars do not form in isolation but as part of a group of stars referred as star clusters or stellar associations.

This is a list of star-forming regions in the Milky Way Galaxy and the Local Group. Star formation occurs in molecular clouds, which become unstable to gravitational collapse, and these complexes may contain clusters of young stars and regions of ionized gas called H II regions. Stars typically form in groups of many stars, rather than in isolation.