as a pronoun, 'anything' is used to refer to a thing of any kind, regardless of its nature or identity. It often represents an unknown or unspecified item or matter.
'anything' can be used in positive, negative, and interrogative sentences. It's often used in situations where the exact object or matter isn't specified.
I haven't eaten anything since morning.
Is there anything I can help you with?
She can do anything if she sets her mind to it.
'anything' is often contrasted with 'something.' While 'something' is used in affirmative contexts to indicate an unspecified item, 'anything' is more neutral and can be used in various contexts, including negative and interrogative ones.
in its adverbial form, 'anything' is used to emphasize the degree or extent of an action.
this usage is less common than the pronoun form and is typically found in informal contexts.
He runs anything but slowly. (Meaning he runs very fast.)
The movie was anything but boring. (Meaning the movie was very interesting.)
when used as an adverb, 'anything' is often paired with 'but' to emphasize the opposite of the adjective or adverb that follows. This construction can be a bit colloquial, so it might not be suitable for very formal writing.