C character set, Keywords, Identifiers

C character set :-
The valid characters for C are alphabets ( A-Z, a-z) , numbers (0 - 9) and special symbols .

Reserved words ( Keywords) :-
Keywords are the words whose meaning has already been known to the C compiler. They are also called instructions. e.g. int , return
They are reserved words and can not be used as variable names.
There are 32 keywords available in C.

Identifiers :-
Identifiers are the names you supply for variable types, functions and labels in your program.You can not use keywords as identifiers.