Constellations are a distinct group of stars that form a pattern in the sky.
They were given names and stories were associated with them, maybe to make them easier to remember. Long ago, when the Egyptians and other ancient astronomers were beginning to study the sky, they divided the sky into regions containing groups of stars and called the groups, constellations. Actually, the constellations are merely areas in the sky that happen to have stars in particular directions as we view them from earth. Well, yes and no. The stars have always been there, but not in the exact position we see them in today.