It is the rare occasion when I get to explain again on the internet that constellations are like, an entire region of the sky. Thus it includes all the stars in that region. What we have now collectively conceived as the representing image of constellations is technically an asterism. Asterism is the line pattern by which we find constellations, an schematic representation of the relative pattern of some stars to others. Some constellations are defined by the asterism included in them (southern cross, e.g.) but many asterism exist that do not define constellations (Pleiades). Many popular constellations are the result of a broader perception of all the stars in their region, sort of like when seeing figures in clouds, but most are actually not, and are named due to the associated cultural tradition. However, they are less noticeable now with light pollution being the norm. All constellations have a designated asterism, usually made of the brightest stars inside the constellation that help find the general location of the constellation, but the constellation itself is the region of the sky.