Articles: A, An, The

A / An

Structure: a + consonant sound, an + vowel sound

a banana, an apple, an hour

Goes by sound, not spelling: that’s why it’s “an hour,” not “a hour.”

The

Structure: the + something specific or already known

Close the door.

Used when the listener knows exactly which one you mean.

Zero Article

Structure: (no article) + general, plural, or uncountable

I love music. Dogs are loyal.

For general statements, not one specific thing.

First Mention → Second Mention

Structure: a → the

I saw a dog. The dog was barking.

“A” introduces something new; “the” refers back to it.