User interface

means by which a person uses a computer and its applications

The user interface (or Human Machine 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 manipulate a systemOutput, allowing the system to produce the effects of the users' manipulation.
See more at Wikipedia.org...

Noun
1. (computer science) a program that controls a display for the user (usually on a computer monitor) and that allows the user to interact with the system
(synonym) interface
(hypernym) program, programme, computer program, computer programme
(hyponym) command line interface, CLI
(classification) computer science, computing

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.
See also user interface copyright.
(1995-02-20)

the program that allows the user to communicate with the machine.