Use a/an for general or first mention; the for specific or known items
A before consonant sound; an before vowel sound; the for specific/known nouns
Same articles; use not + article + noun as needed
Is there a/an ...? / Where is the ...?
💡 Choose by sound, not spelling (an hour). Omit article with plural/uncountable when speaking generally.
✓I bought a book.
✗I bought the book (first mention).
Use a/an for first mention/general.
✓She is an honest person.
✗She is a honest person.
Use an before vowel sound /ɒ/.
✓Where is the station?
✗Where is a station?
The listener knows which station (specific).
✓Water is essential.
✗The water is essential (general statement).
Zero article for uncountable when speaking generally.