The rule, as people use it
Use "a" or "an" when you mention one thing for the first time, or when it's any one of many: "I saw a dog." Use "the" when you and the listener both know which one you mean: "The dog was huge." That shared knowledge is the whole idea. You say "the moon" and "the kitchen" because there's only one in the picture.
"An" goes before a vowel sound, not a vowel letter. So it's an apple and an hour, because "hour" starts with a vowel sound, but a university, because "university" starts with a "y" sound. Trust your ear here.
The mistake learners make most is leaving the article out: "I have car" or "She's teacher". English wants a word before a single count noun, so say "a car", "a teacher". With plurals and non-count nouns talked about in general, you leave it out: "Dogs are loyal." "I love music."
Examples
Tap a sentence to hear it. Say it after the voice.
Fill the gap
Type the missing words, then check. The full sentence plays when you get it.
- 1
I'm waiting for (a / an) taxi.
- 2
It's (a / an) old building.
- 3
She works as (a / an) engineer in Osaka.
- 4
Can you turn off (a / the) lights in the kitchen?
- 5
I bought a shirt and a hat. (A / The) shirt was on sale.
- 6
My brother is (a / the) doctor.
- 7
We waited for (a / an) hour.
- 8
Is there (a / the) pharmacy near here?
Practice · 3 min
Describe the street where you live in six sentences, out loud. Introduce each place with "a" or "an", then talk about it again with "the": "There's a café on the corner. The café opens at seven." Write the six sentences down and circle every article. Check that each "an" comes before a vowel sound.
Say it today
Use it once in a real conversation before tomorrow. Out loud counts, even to yourself.