The "#include" statement in C++ is used to include a header file in a program. It allows the program to access the declarations and definitions present in the header file.

The header files contain predefined functions and classes that can be used in the program. These files provide the necessary information about the functions and classes that the program uses.

To use a header file, you need to include it at the beginning of your program. This is done by using the "#include" directive, followed by the name of the header file enclosed in angle brackets or double quotes.

For example, if you want to use the "iostream" header file in your program, you would write:

include

This allows you to use the functions and classes defined in the "iostream" header file, such as "cout" and "cin", for input and output operations.

Including the necessary header files in a program is an important step in C++ programming, as it ensures that the program has access to the required functions and classes.