Why do we use iostream and namespace in C++

#include<iostream>

or
# include<iostream.h>

• Istream class supports Input function.
• Ostream class supports output function.

            All objects are included in iostream file So, we can use input or output statement in our programs.

using namespace std;

• It includes all C++ standard libraries.
• We do not use this in old IDE like Turbo C++ but we have to use this in all new IDE like Code Blocks, Dev C++ etc.