There are many different types of stars in the Universe, from Protostars to Red Supergiants. They can be categorized according to their mass, and temperature.

Stars are also classified by their spectra (the elements that they absorb). Along with their brightness (apparent magnitude), the spectral class of a star can tell astronomers a lot about it.

There are seven main types of stars. In order of decreasing temperature, O, B, A, F, G, K, and M. O and B are uncommon, very hot and bright. M stars are more common, cooler and dim.

The video below presents a helpful overview of the types of stars in the Universe.

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