To theoretical computer scientists, Chomsky is best known for his work on the Chomsky hierarchy, which organizes language classes according to the different types of grammars that generate them. In particular Chomsky was the first to specify the class of grammars which today are called context-free.
During the Vietnam War, Chomsky became interested in politics and the mechanisms by which governments maintain and distribute power. He has written many books on politics, language, philosophy, and the media. Among the best known are Manufacturing Consent (1988) and Necessary Illusions (1989).