What is natural language?

While grammarians, writers of dictionaries, and language policy-makers all have a certain influence on the evolution of language, their ability to influence what people think they 'ought' to say is distinct from what people actually say. Natural language applies to the latter, and is thus a 'descriptive' term. Thus non-standard language varieties (such as African American Vernacular English) are as natural as standard language varieties (such as Standard American English).