Articles are small glue words that hold sentences together. They usually introduce a noun.

There are three articles in the English Language: a, an, & the.

Two of these articles, "a" and "an," are called indefinite articles. This is because we use them when we are talking about a noun that we do not have much knowledge about.

For example:

If we are talking about one cat out of many cats, or a cat that we don't know much about we might say, "Look, there's a cat!"

Or maybe we are talking about one orange that falls from a tree. We could say,"Look, there's an orange on the ground." We would use "an" in this case because the word "orange" starts with a vowel.

However, if we want to talk about something that we have some definite knowledge about, we would use the definite article, "the".

An example of a sentence using the definite article could be used when we are talking about a cat and an orange that we have seen before:

"Look Jeff, the cat is back, and its eating the orange!"

References:

Grammarly.com. (n.d.) articles.

https://www.grammarly.com/blog/ind

efinite-articles-a-and-an/