C header files generally use the .h extension. They are commonly included to make declarations and related definitions available to source files.
Programming in C MCQ - Library & Header Files
The presentation describes header files as containing function declarations and macro definitions, rather than only variables, comments, or executable code.
stdio.h is the standard input/output header and provides declarations for standard I/O facilities such as printf() and scanf().
math.h is associated with mathematical functions. It provides declarations for mathematical library operations.
string.h contains declarations for standard string-handling functions and related memory operations.
