The Waite Group's C++ Primer Plus, Third Edition

Chapter 16

A1:	The iostream file defines the classes, constants, and manipulators used to manage input and output. These objects manage the streams and buffers used to handle I/O. The file also creates standard objects (cin, cout, cerr, and clog and their wide-character equivalents) used to handle the standard input and output streams connected to every program.
A2:	Keyboard entry generates a series of characters. Typing 121 generates three characters, each represented by a 1-byte binary code. If the value is to be stored as type int, these three characters have to be converted to a single binary representation of the value 121.
A3:	By default, both the standard output and the standard error send output to the standard output device, typically ...