A "preprocessor macro" enables the effect of cut-and-paste of source code, from that macro's definition (in a
#define statement) to anywhere the programmer "expands" that macro.
This cutting-and-pasting action could be parameterized. If a macro has been defined to accept a parameter, its expansion is allowed to pass nothingness. A "variadic macro" is written to accept a variable number of macro-parameters.
Additional information about macros (includes interactive examples)