A model is a person with a role either to display commercial products (notably fashion clothing in fashion shows) or to serve as an artist's model. Modelling ("modeling" in American English) entails using one's body to represent someone else's body or someone's artistic imagination of a body.
In scholarly research and applied science, a model should not be confused with a theory: while a model seeks only to represent reality with the purpose of better understanding or predicting the world, a theory is more ambitious in that it claims to be an explanation of reality.