please explain about iostream

[i2v7M4Gy]

"Iostream includes the declarations of the basic standard input-output library in C++" Please explain this.Wat iostream contains?

[awasteoflife]

the iostream library includes the necessary classes for input and output, such as cin and cout.

[Bazzy]

You can find everything at http://www.cplusplus.com/reference/iostream/

[wretch]

Speaking of <iostream> vs. <stdio.h> does an experienced C++ programmer look down on using:

printf("\nfirst int: %d 2nd: %d 3d: %d\n", int1, int2, int3);
instead of:
cout << endl << "first int: " << int1 << " 2nd: " << int2 << " 3d: " << int3 << endl;

For input I prefer cin >> ... but for output it seems easier to specify formatting with printf, is this a bad habit?