Just What Exactly Is an Interface? (definition)

The word “interface” is one of those words that is thrown around a lot without much discussion. I say “interface”, you say “interface”, and we pretty much get where we need to go. Lately, though, when people ask me what I write about on my blog, I say “interface design” and I then have to define what I mean by that. So, to make my life easier as well as to make sure we are all on the same page, here are several definitions from around the Web.

interface noun. Dictionary.com

A surface forming a common boundary between adjacent regions, bodies, substances, or phases.

Computer Science:
The point of interaction or communication between a computer and any other entity, such as a printer or human operator.
The layout of an application’s graphic or textual controls in conjunction with the way the application responds to user activity: an interface whose icons were hard to remember.

interface noun. Wikipedia

an interface is the point, area, or surface along which two substances or other qualitatively different things meet; it is also used metaphorically for the juncture between items.

So, interfaces are where things happen. Where the most interesting things happen is interfaces that involve humans, otherwise known as user interfaces.

user interface noun. Dictionary.com

The aspects of a computer system or program which can be seen (or heard or otherwise perceived) by the human user, and the
commands and mechanisms the user uses to control its operation and input data.

A graphical user interface emphasises the use of pictures for output and a pointing device such as a mouse for input and control whereas a command line interface requires the user to type textual commands and input at a keyboard and produces a single stream of text as output.

user interface noun. Wikipedia

The user interface is the aggregate of means by which people (the users) interact with a particular machine, device, computer program or other complex tool (the system). The user interface provides means of:

Input, allowing the users to control the system

Output, allowing the system to inform the users (also referred to as feedback)

To bring this full circle, all the latest interfaces I’ve been writing about (like the Google Maps interfaces), are user interfaces which generally utilize a screen for output (display) and a mouse and keyboard for input.

Got your own definition or one that adds a different light to these?