HCI - Human-Computer Interaction:
"HCI (Human-Computer Interaction) began as a discipline in the late 1970s and early 1980s. Initially it came about through an alliance between Computer Scientists and Psychologists. Since then ethnography, ergonomics and activity theory have all been recruited to the cause. HCI research is concerned with how to ensure usability, that is to say, products that are effective, efficient and satisfying to use. HCI researchers try to understand what users want to do and how designers can be helped to provide products that satisfy these needs.".
(MONK, 2002)

Interface:
"Many people assume that the term user interface refers specifically to Graphical User Interfaces (GUIs), complete with windows and mouse-driven menus. An example: "Before too long , you may not have to worry about an interface at all: you may find yourself simply speaking with your computer". As I pointed out in response, a voice controlled system may have no windows, but neither do the telephone voice-response system, and they often have hellaciously bad interfaces. The way that you accomplish tasks with products - what you do say and how it responds - that's the interface.".
(RASKIN, 2000)

Usability:
Usability envolves apprehension of new methods and techniques emphasizing the human being communication related with the technological systems, from the analysis of the activities that involves tasks interactions with informatics programs, information and products.

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