A / An
Use a or an with singular countable nouns. Use an before a vowel sound.
General reference: A veterinarian takes care of animals. (any veterinarian, in general)
First mention: I heard there is a new veterinarian in town. (mentioning for the first time)
She is an engineer. (vowel sound → an)
The
Use the when both speaker and listener know which specific thing is being referred to.
Specific singular noun: The school counselor talked to us about careers. (our specific counselor)
Representing a whole group: The elephant is known for its intelligence. (elephants as a species)
Specific plural noun: The jobs that involved working with animals sound interesting.
Only one of something: Wolves sometimes seem to howl at the moon.
No Article (Ø)
Use no article when speaking generally about plural countable nouns or uncountable nouns.
Plural nouns — general: Ø Dolphins and whales are very intelligent.
Uncountable nouns — general: Ø Stress can be an issue when working with animals.
More examples: Ø Music makes people happy. | Ø Water is essential for life.
⚠ Common mistakes:
✗ I saw the dog in the park. (when mentioning a dog for the first time) → ✓ I saw a dog in the park.
✗ She plays a piano every day. (general activity) → ✓ She plays the piano every day.
✗ The dogs are loyal animals. (general statement about dogs) → ✓ Ø Dogs are loyal animals.