It really does depend on how you use it, but most of the time it is an abstract noun: 'It could have been anything'
No part of grammar
The word grammar is a noun.
Spelling is not officially a part of grammar.
The correct grammar is "You didn't have to send us anything." Using "nothing" is a double negative and is considered grammatically incorrect.
I is watch monitor.
"Of" is a preposition.
linking verb
linking verb
connectives
Grammar
anything with right spelling and grammar.
Grammar is an inherent part of human language, so it is as old as human beings are. Certainly not in this question.