Articles a/an

1. Use "a", and only with singular nouns

1.1. Examples

1.1.1. "It's a book

1.1.1.1. It's a watch

1.1.1.1.1. Other examples

2. Are considered indefinite articles and they are used to introduce new concepts into a discourse

3. Use "an" with words that start with a vowel sound

3.1. Examples

3.1.1. An elephant

3.1.1.1. An alligator

3.1.1.1.1. Other examples