@chrisamaphone Generative grammar! (ling hobbyist speaking 😈) It's a method of analyzing/generating the syntax structure of sentences in natural languages, basically by keep packaging words/phrases into different types of non-terminal symbols (e.g. NP i.e. nominal phrase). An obvious limitation is that it's not capable for explaining the semantic of sentences. A famous example would be Chomsky's "Colorless green ideas sleep furiously", which is a sentence that is totally correct in syntax, but nonsense in semantics.