Caricature is a picture, description, or imitation of a person in which certain striking characteristics are exaggerated in order to create a comic or grotesque effect.
Explanation:
In order to draw a caricature you start by sketching the general shape of their head on a piece of paper. Then, look at the person, and choose one or two features that immediately jump out at you, like their nose, their lips, or their eyes. Once you've chosen one or two features, exaggerate them in your drawing.