Any programming language has a set of pre defined keywords which could not be used in any other form or any other purpose. Any program in C is constructed from a set of reserved keywords. The basic instructions which setup the purpose command for compiler are derived from these keywords. The pre-defined keywords can be only used for their intended purpose. The meaning of keywords is already communicated to the compiler.
In C we have total of 32 keywords which are as follows:
Keywords: void, return
Keywords: int, char, float, double
Keywords: for, while, do
Keywords: if, else, switch, case, default
Keywords: goto, continue, break
Keywords: signed, unsigned, short, long
Keywords: typedef, enum
Keywords: auto, extern, register, static
Keywords: struct, union
Keywords: const, volatile, sizeof
We will read about each of them in following tutorials.