#include is a preprocessor in c program that includes the content of the other file to the source code where #include is declared
#include copies the content of an entire file to the location of the #include call.
In practice, it is most commonly used to include header files, that is to reference function prototypes, data types, constants, etc that are stored in a single file.
will reference all the C library functions and constants that are related to C-string manipulations.
#include is an Header file which is inbuild command user cant change
its used to include the functions and many more like math.h & conio.h & stdio.h
#include directive tells the preprocessor to insert the contents of another file into the source code at the point where the #include directive is found. Include directives are typically used to include the C header files for C functions that are held outsite of the current source file.