Grammar articles: a/an, the

The words in bold in the sentences are called articles (a/an, the). We use articles before nouns.
1. We use a/an for indefinite singular nouns.

• Put a before nouns which begin with consonant sounds. For example: a book, a crocodile, a flower, a mouse, a snake, a shirt, a unicorn.
• Put an before nouns which begin with vocal sounds (a, i, u, e, o). For example: an ant, an architect, an elephant, an envelope, an hour, an gaji.