The or No Article?

Articles essentially behave like adjectives in the sense that they modify nouns. In English, the articles are “the” and “a/an.”

The way articles work depends on whether they come before count nouns or noncount nouns. Count nouns typically have singular and plural forms (for instance, “lake/lakes” and “concept/concepts”), whereas noncount nouns do not have plural forms (for instance, “information” or “milk”).

"The" can be used before both singular and plural forms of nouns, while "a/an" are only used before singular countable nouns. Therefore, it is generally true that "a/an" are only used before countable nouns in the singular form.