"A," "An," "The" - The Articles - grammar
www.grammar.com › A-An-The-The-ArticlesThe indefinite article—the words a or an —always comes before a singular noun, never a plural noun. You might want to refer to a general group of things named by the particular noun. Thus, you refer indefinitely to a beer, an apple, or a political party in general without specifying which beer, which apple, or which political party.