Determiners
Determiners are terms that precede a noun or noun phrase and serve to clarify the noun's context. They are applied to the noun to describe, name, or quantify it.
Articles (a, an, the), demonstratives (this, that, these, those), possessives (my, your, his, her, its, our, their), and quantifiers are the most prevalent kinds of determiners (some, any, much, many, few, several, all, both, either, neither).
The specificity or generality of a word is indicated by the use of articles. While "the" is a definite article and refers to a particular word, "a" and "an" are indefinite articles and refer to a general noun.