What is the role of an article in a sentence?

Articles (a, an, the) are adjectives that specify whether a noun is referring to something specific or general. Their role is to define the noun's scope and definiteness. They help the listener or reader understand whether the noun is:

* Indefinite (a/an): Referring to any member of a group. "I saw a dog." (any dog)

* Definite (the): Referring to a specific member of a group already known or previously mentioned. "I saw *the* dog I lost yesterday." (a particular dog)

In essence, articles clarify the noun and contribute to the overall clarity and meaning of the sentence.