The

The word the has two homonyms (unrelated words with the same spelling):

Adverb

This is a fossil word, now used only to modify comparative adjectives, as in The more [guests there are], the merrier [the party will be].

Definite Article

Monadic

The can be used to introduce the name of a unique thing, as in The Statue of Liberty or the moon.

Anaphoric

More commonly, the is used to refer to something previously mentioned (its antecedent), as in Fred and his dog were walking in a park when the dog started chasing a squirrel, where the indicates that both references are to the same dog .