A stellar designation given to stars that uses the Greek alphabet followed by the genitive form of the parent constellation's Latin name. It originates from the naming protocol used in the 1603 star atlas "Uranometria" compiled by German astronomer Johann Bayer. The original list of Bayer designations contains 1,564 stars with Alpha (α) denoting the brightest constellation star, Beta (β) the second brightest and so on.
Although Bayer ordered the stars in terms of brightness that are some notable abnormalities. For example, Rigel (β Ori) is almost always brighter than Betelgeuse (α Ori) and Pollux (β Gem) is notably brighter than Castor (α Gem).
The Greek alphabet has twenty-four letters and when all were used up, Bayer started using Latin letters: upper case A, followed by lower case b through z (omitting j and v) for a total of another 24 letters. He never required more letters than this but later astronomers did and they added both upper and lower case Latin letters. Bayer catalogued stars he could see from Germany but later astronomers (notably Lacaille and Gould) supplemented it with southern constellations entries.