Stars, also known as suns, are the center of solar systems.
They are described with a standard nomenclature that incorporates three factors: Type, Spectral Classification, and Size.
Dwarf stars are identified only by their size and type; no spectral classification is assigned. For instance, a DM is a red dwarf star of type M.
Spectral classification is expressed as a decimal number from 0 to 9.
The Earth's sun is a G2 V, indicating type G, spectral class 2, size V main sequence.