The Free On-line Dictionary of Computing (30 December 2018):
look and feel
The appearance and function of a program's
user interface. The term is most often applied to
graphical user interfaces (GUI) but might also be used by
extension for a textual command language used to control a
Look and feel includes such things as the icons used to
represent certain functions such as opening and closing files,
directories and application programs and changing the size
and position of windows; conventions for the meaning of
different buttons on a mouse and keys on the keyboard; and
the appearance and operation of menus.
A user interface with a consistent look and feel is
considered by many to be an important factor in the ease of
use of a computer system. The success of the Macintosh user
interface was partly due to its consistency.
Because of the perceived importance of look and feel, there
have been several legal actions claiming breech of copyright
on the look and feel of user interfaces, most notably by
Apple Computer against Microsoft and Hewlett-Packard (which
lost) and, later, by Xerox against Apple Computer. Such legal
action attempts to force suppliers to make their interfaces
inconsistent with those of other vendors' products. This can
only be bad for users and the industry as a whole.