Final answer:
There are three basic types of star clusters: globular clusters, open clusters, and stellar associations. Globular clusters contain very old stars, open clusters contain hundreds of stars and are located in the plane of the Galaxy, and stellar associations contain extremely young stars.
Step-by-step explanation:
The three basic types of star clusters are globular clusters, open clusters, and stellar associations. Globular clusters contain only very old stars and are distributed in a halo around the Galaxy. Open clusters are located in the plane of the Galaxy and typically contain hundreds of stars. Stellar associations are found in regions of gas and dust and contain extremely young stars.
Globular clusters are spherical collections containing hundreds of thousands of stars. They have diameters ranging from 50 to 450 light-years and are typically found in a halo around the Galaxy. All stars within a globular cluster are very old, which provides insight into the early stages of the Galaxy's formation.
Open clusters are less dense than globular clusters and usually consist of a few hundred stars. They are found in the plane of the Galaxy with diameters of less than 30 light-years. Open clusters contain younger stars compared to globular clusters and offer a snapshot of more recent star formation events in the Milky Way.
Stellar associations are loose groupings of extremely young stars located in regions of gas and dust. These associations are important for studying the earliest stages of star development and how new stars are born in the Galaxy.