What is iostream header file?

iostream header file use in C++ program for input and output functions.iostream use the object like cin ,cout ,cerr and clog to send data to and from the standard streams input, output, error (unbuffered), and log (buffered) respectively.

             Example;
                  
                           #include<iostream.h>
                                 
                          void main( )
                            {
                                 int a;
                                 cout<<"Enter number";
                                 cin>>a;
                             }
Here we use cout for print output and cin for input.