Indefinite article a/an

First mention of a countable singular noun.

a + [consonant sound] | an + [vowel sound]

a/an is used before a singular countable noun on its first mention, or when talking about one of many. a goes before a consonant sound, an before a vowel sound (the sound matters, not the letter).

Examples

  • She is an engineer.
  • We need a truck for this load.
  • It took an hour to clear customs.

  • She is engineer.

    She is an engineer.

    A singular countable noun on first mention needs an article: an engineer.

Common mistakes

  • Dropping the article before a singular countable noun: She is engineer → She is an engineer.
  • Choosing a/an by letter instead of sound: a hour → an hour, a university stays a university (sound /j/).
Practice