denoting one or more people or things already mentioned or assumed to be common knowledge.
what's the matter?
used to point forward to a following qualifying or defining clause or phrase.
the fuss that he made of her
used to make a generalized reference to something rather than identifying a particular instance.
he taught himself to play the violin
enough of (a particular thing).
he hoped to publish monthly, if only he could find the money
(pronounced stressing “the”) used to indicate that someone or something is the best known or most important of that name or type.
he was the hot young piano prospect in jazz