The words "the" and "a" are both articles in the English language. Articles are a type of determiner, which are words used to modify nouns and provide context about their definiteness or specificity.

1. "The": This is known as the definite article. It is used to refer to specific or particular nouns. For example:

   • "The book on the table is mine." (Here, "the" specifies a particular book that is on the table.)

2. "A": This is known as the indefinite article. It is used to refer to non-specific or general nouns. For example:

   • "I saw a dog in the park." (Here, "a" refers to any dog, not a specific one.)

There is also another indefinite article, "an", which is used before words that begin with a vowel sound:

• "An apple a day keeps the doctor away." (Here, "an" is used because "apple" starts with a vowel sound.)

In summary, "the" and "a" are articles, with "the" being definite and "a" (or "an") being indefinite. They help clarify whether a noun is specific or general in a sentence.