In C language Tutorial we told you about stdio.h and conio.h header files.

In CPP we will focus on iostream.h header file.

iostream is a header file which is used for input/output in the C++ programming language.

It is part of the C++ standard library. The name stands for Input/Output Stream.

In C++ and its predecessor, the C programming language, there is no special syntax for streaming data input or output. iostream provides basic input and output services for C++ programs. iostream uses the objects cin, cout, cerr, and clog for sending data to and from the standard streams input, output.

As we can see in the above program it uses cout to print Hello World! on screen.