Definite and Indefinite Articles (a/an/the)

An article is an adjective (a determiner) that comes before and modifies a noun or noun equivalent.

Articles indicate whether a noun is specific or unspecific. The definite article (“the”) defines a noun as specific, which means that the identity of the noun is known. An indefinite article (“a” or “an”) defines a word as unspecified, which means that the identity of the noun is unknown.

The first example states that there is one specific flower that smells nice. The second is a general statement: “any flower smells nice” or “all flowers smell nice.”

The definite article “the” indicates that a noun has a specific identity and/or that it has already been referred to once before in the context of a given piece of writing.

Here, the “gallery teaching program” is a specific program that was designed for a specific museum (i.e., the Whitney Museum of American Art).

The “composite” is one specific composite. It can be presumed from this sentence that this composite was previously identified.

“Likelihood of Alzheimer’s” is an uncountable noun. However, here it is a specific uncountable noun.

When to use definite articles

Indefinite articles “a” and “an” are used to indicate that a noun has an unspecified identity.

Here, “external heating system” is not a specific heating system; any heating system would be useful but would also continuously consume power and weigh down the vehicle.

Robert Frost wrote many poems and “Fragmentary Blue” is one of them.

It can be presumed from the indefinite article “an” that this “irregularity” was not previously established. Any future reference to this particular irregularity should use the definite article “the.”

Choosing “a” or “an”

The choice between “a” and “an” depends on the sound the following word begins with. The article “a” precedes words that begin with a consonant sound; the article “an” precedes words that begin with a vowel sound. For example, the word “apple” should be preceded by “an.” This is because the word “apple” begins with a vowel and a vowel sound.

Using indefinite articles with uncountable nouns

Indefinite articles typically cannot be used with uncountable nouns.

This is incorrect because “snow” is an uncountable noun. There are, however, certain uncountable nouns that are sometimes treated as countable. This is generally only applicable to casual, non-academic contexts.

It can be assumed here that “a coffee” is being used to mean “a cup of coffee.” The same applies to “a sugar”; “a sugar” can be assumed to mean “a cube of sugar.”

A noun that is modified by an article is often also modified by another adjective. In such cases, the article typically comes from and then is followed by the adjective and noun.

Articles cannot be used with pronouns. This is because both articles and pronouns indicate specificity and using both would only cause confusion.

However, depending on the context, a definite article and a pronoun may be used interchangeably.

In some cases, an article can be omitted before a noun because the article is implied and does not need to be explicitly written. Articles are usually omitted before (1) languages / nationalities, (2) academic subjects / fields of expertise, and (3) certain abstract ideas.

Referring to languages and nationalities

Articles are always omitted before languages.

Depending on the context, articles are also omitted before nationalities.

The above sentence implies that there are multiple people but only one American (and her name is Lana).

These sentences, on the other hand, simply mean that Lana’s nationality is American.

Referring to academic subjects and other fields of expertise

Academic subjects and other fields of expertise, such as sports, are also not preceded by articles.

Referring to some abstract ideas

Articles are generally unnecessary when writing about abstract ideas because an abstract idea is not a specific thing, and articles are used to indicate specificity.