Indefinite articles introduce nouns in a general way and signal that we are not talking about something specific. This short guide covers the basic use of a, an, and some so you can pick the right form for singular and plural nouns.
Use
An indefinite article appears when you mention something for the first time or when the exact identity does not matter to the listener. Use a or an for singular countable nouns and some for plural or uncountable nouns when needed.
A
Use a before singular nouns that begin with a consonant sound to refer to one typical item. The noun must be countable because you cannot say a with uncountable or plural nouns.
Examples
An
Use an before singular nouns that begin with a vowel sound to make pronunciation smooth. Like a, an signals one countable item and cannot be used with uncountable or plural nouns.
Examples
Some
Use some with plural countable nouns or uncountable nouns when talking about an indefinite amount. Some can appear in positive sentences, offers, and requests, and you usually omit the article for general plural references.
Examples
Summary
Indefinite articles mark non-specific items: use a for singular countable nouns starting with a consonant sound, an for singular countable nouns starting with a vowel sound, and some for plural or uncountable nouns when you need to express an indefinite quantity.
Last updated: Fri Oct 24, 2025