Corpus linguistics is the study of language as expressed in samples (corpora) or "real world" text. This method represents a digestive approach to deriving a set of abstract rules by which a natural language is governed or else relates to another language. Originally done by hand, corpora are largely derived by an automated process, which is corrected. The core of a corpus is the derivation of a set of Part-of-speech tags, representing a formal overview of the various types of words and word-relationships in a given language.
The corpus approach runs counter to Noam Chomsky's view that real language is riddled with performance-related errors, thus requiring careful analysis of small speech samples obtained in a highly controlled laboratory setting. Corpus linguistics does away with Chomsky's competence/performance split; adherents believe that reliable language analysis best occurs on field-collected samples, in natural contexts and with minimal experimental interference.