What Does User Interface (UI) Mean?
User interface (UI) is a broad term for any system, either physical or software based, that allows a user to connect with a given technology. Many different kinds of user interfaces come with various devices and software programs. Many of them have some basic similarities, although each one is unique in key ways.
Techopedia Explains User Interface (UI)
One main type of user interface is called a graphical user interface (GUI). This includes the interfaces for the modern operating systems many of us are familiar with, particularly Windows, as well as other kinds of software programs that are made to be driven mainly by icons or images rather than text commands. Users can contrast the graphical user interface to a text interface such as the MS-DOS system that was used to operate personal computers of earlier decades.
Other kinds of user interfaces include touch screen interfaces, a common type of UI for mobile devices, and other physical types of interfaces for hardware pieces. For example, a remote control for a DVD player, audio system, television or game console can be thought of as a user interface for that device. Other kinds of software-oriented user interfaces are becoming more and more sophisticated, often using a combination of graphical and text elements to drive specific user activities.