A type of
grammar first described by linguist
Noam Chomsky that is used for describing
programming languages.
The grammar consists of rules such as "a sentence is a noun phrase followed by a verb phrase" rendered as S -> NP VP. Another rule might be "a noun phrase consists of an article followed by zero or more adjectives followed by a noun."
source: Out of Their Minds: The Lives and Discoveries of 15 Great Computer Scientists, by Dennis Shasha and Cathy Lazere