A context-free grammar composed of:
- A set of terminal symbols referred to as “tokens”.
- A set of nonterminals called “syntactic variables”.
- A set of productions, where each production consists of a nonterminal, called the head or left side of the production, an arrow, and a sequence of terminals and/or nonterminals, called the body or right side of the production.
- A designation of one of the nonterminals as the start symbol.