A caricature is an exaggerated portrait of a person or group in either a visual or literary form. Caricature is actually quite an ancient art, with some examples of caricature being thousands of years old, ranging from the plays of Aristophanes to the editorial pages of the local paper. This art form is quite diverse, with a number of famous practitioners throughout history, ranging from Leonardo Da Vinci to Thomas Nast. You can probably find an example of caricature in your vicinity, especially if you have a paper handy, because most political cartoons take advantage of caricature.
The word is derived from the Italian caricare, which means “to load or exaggerate,” and it has been used in English since the 1500s, although examples of caricature predate the word's introduction to the English language. As the Italian root suggests, a caricature is an exaggerated portrait with a loaded or dual meaning which can get quite complex, especially in the hands of a master.
One of the distinguishing features of caricature is the tendency to overemphasize well-known features of the subject. For example, someone who is famous for having a very distinctive nose might find the size of that nose grossly exaggerated in a caricature. Teeth, lips, and ears may also be blown out of proportion in a caricature, leading some people to call the resulting image grotesque or unpleasant.
Many political cartoons use caricature to drive home a point. For example, during the Edwardian Era, critiques of the wealthy showed immensely fat people lolling on beds of money, making a satirical and sharp comment about the upper classes. Many people are at least vaguely familiar with the physical appearance of major politicians, making caricature a highly effective form of commentary, as people recognize a feature in the drawing and make the connection with the politician, even if they don't fully understand the details of the issue the caricature is highlighting.
Like other forms of satire and comic art, caricature is protected by law in many areas, along with other freedoms of expression. This can sometimes result in quite a controversy, as in 2005 when a Danish newspaper printed a number of caricatures of the Muslim prophet Muhammad (Peace Be Upon Him), igniting a global rage among Muslims who found the images offensive. Caricature has also been a famous forum for racist stereotypes, as can be seen in cartoonish versions of African-Americans published in the United States well through the 20th century, or in images of caricatured Jewish people used in propaganda campaigns by the German government during the Second World War.