Articles are words like "a", "an", and "the" that specify the definiteness or indefiniteness of a noun. They tell us whether we are talking about a specific noun or any noun of that type.
Here are some examples:
* "a" - modifies the noun "cat" in the sentence "I saw a cat." This refers to any cat, not a specific one.
* "an" - modifies the noun "apple" in the sentence "I ate an apple." Again, this refers to any apple.
* "the" - modifies the noun "dog" in the sentence "The dog barked." This refers to a specific dog, one that has already been mentioned or is understood by the listener/reader.
Articles are considered determiners, which are a type of word that comes before a noun and provides information about it.