Regular grammar is a type of formal grammar used to describe regular languages. It consists of a set of production rules that define how strings can be generated. These rules typically involve terminal symbols, which are the actual characters in the language, and non-terminal symbols, which are placeholders that can be replaced by other symbols. Regular grammar can be divided into two categories: right-linear and left-linear. In right-linear grammar, the non-terminal symbols appear on the right side of the production rules, while in left-linear grammar, they appear on the left. Regular grammars are closely related to finite automata and regular expressions, which are tools used in computer science for pattern matching and language recognition.