In software design, the look and feel of a graphical user interface comprises aspects of its design, including elements such as colors, shapes, layout, and typefaces (the "look"), as well as the behavior of dynamic elements such as buttons, boxes, and menus (the "feel"). The term can also refer to aspects of a non-graphical user interface (such as a command-line interface), as well as to aspects of an API – mostly to parts of an API that are not related to its functional properties.

<operating system> 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 program. 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 Apple 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. (1995-03-03)

The Government of Canada's Common Look and Feel (CLF) Standards for the Internet governed the branding, usability & accessibility standards for its websites and web applications from 2000 - 2010. It comprised the following four parts, now rescinded: