An article is any member of a class of dedicated words used with noun phrases to mark the identifiability of the referents of the noun phrases. The category of articles constitutes a part of speech. For example, in English, both "the" and "a/an" are articles, which combine with nouns to form noun phrases.

English Grammar Terms II

In linguistics, the grammar of a natural language is its set of structural constraints on speakers 'or writers' composition of clauses, phrases, and words. The term can also refer to the study of such constraints, a field that includes domains such as phonology, morphology, and syntax, often complemented by phonetics, semantics, and pragmatics. There are currently two different approaches to the study of grammar, traditional grammar and theoretical grammar.