Avram Noam Chomsky is an American linguist best known for transforming the study of grammar into a precise, mathematical subject. Although his primary field is the study of human language, his formal results reached far beyond linguistics and shaped how computer scientists think about the syntax of programming languages.
In 1956 Chomsky published “Three Models for the Description of Language” in the IRE Transactions on Information Theory, a copy of which is hosted on his own website. The paper compares three kinds of grammar of increasing power, finite-state, phrase-structure, and transformational, and argues that the simplest model, a finite-state process, is inadequate to describe the structure of natural language sentences. In doing so he laid out the levels of generative power that became known as the Chomsky hierarchy.
This way of ranking grammars by the kind of machine needed to recognize them connected linguistics directly to the emerging field of automata theory. The Stanford Encyclopedia’s account of computation places these formal grammars alongside the abstract machines that recognize them, and the correspondence between the two is exactly what compiler writers exploit.
For programming, Chomsky’s lasting contribution is the idea that a language can be specified by a precise set of production rules and that the choice of grammar type determines what kind of parser is needed. Context-free grammars, one of his levels, became the standard way to define the syntax of programming languages, so that nearly every compiler in use today rests on the framework he set out in 1956.