Articles are a unique type of adjectives that indicate which noun (person, place, or thing) you’re talking about. The only definite article in English is the, and it refers to a specific noun. Indefinite articles (a or an) refer to nouns more generally.
Indefinite articles refer to non-specific nouns. Think “I need a pen” or “I want an orange.” In both cases, we aren’t referring to a specific pen or orange. The indefinite articles let you know that we’d accept any pen or orange.
The above examples also demonstrate when to use a versus an. If the word following the article begins with a consonant sound, you should use a. If it begins with a vowel sound, you should use an. So if you added the word large to describe the orange you want, the sentence would become “I want a large orange.”
The definite article the, on the other hand, refers to a specific noun. If you were to say “I want the orange” instead of “an orange,” you’d be talking about one specific orange. If you requested “the pencil” instead of “a pencil,” you’d be asking for one particular pencil.
Articles for Singular and Plural Nouns
A and an only work with singular nouns because they only refer to one item. Plural, non-specific nouns don’t use articles. So if you want more than one orange but don’t care which ones, “I want an orange” becomes “I want oranges.”
The works with both singular and plural nouns. If you want a specific orange or specific oranges, you could say “I want the orange,” or “I want the oranges.”
Mass nouns are any nouns that can’t be counted. This makes them neither singular nor plural. Liquids are a great example of mass nouns. You’d still use the article the for specific mass nouns, but for non-specific ones, you wouldn’t use an article at all. For example, both “The water is on the floor,” and “Water is on the floor,” are correct. The first refers to specific water, while the second doesn’t.
There’s one exception where you can use a or an before a mass noun. This is when a specific noun is implied in the context of the sentence. A scenario where this happens is at restaurants. Instead of saying “I’ll have a glass of orange juice,” you’d say, “I’ll have an orange juice.” Orange juice is a mass noun, but in this context it’s implied that you’re referring to a glass of orange juice.