While the computer has lost its magical aura it had in its early days, the interfaces have been adapted to the new user and majority allowing the use of computers it easier. This book begins by presenting a state of the issue of Human-Computer Interaction (HCI), a discipline that arises in parallel to the phenomenon of popularization of computer systems and aims to facilitate maximum use of computers. The author of the IPO as a discipline from which encompass one of the key issues of our times: information.