Principles of User Interface Design

from the theory of Larry Constantine and Lucy Lockwood in their usage-centered design, the principles are:

Structure Principle

• organize the user interface purposefully


• make it meaningful and useful based on clear, consistent models apparent and recognizable to users


• put related things together; separate unrelated things


• differentiate dissimilar things, make similar things resemble one another

Simplicity Principle

• make simple, common tasks simple to do


• communicate clearly and simply in user’s own language


• provide good shortcuts that are meaningfully related to longer procedures

Visibility Principle

• keep all needed options and materials for a given task visible


• do not distract user with extraneous and redundant information


• do not confuse user with too many alternatives for performing same task

Feedback Principle

• inform actions or interpretations


• inform changes of state or condition


• inform errors or exceptions


• keep mode of communication – relevant, clear, concise, and in language familiar to user

Tolerance Principle

• reduce cost of mistakes and misuse by allowing ‘undo’ and ‘redo’


• prevent errors by tolerating varied inputs and sequences and by interpreting reasonable actions

Reuse Principle

• reuse internal and external components and behaviors; maintaining consistency with purpose


• reduce the need for users to rethink and remember

The user interface of an application will often make or break it.  Although the functionality that an application provides to users is important, the way in which it provides that functionality is just as important.  An application that is difficult to use won’t be used.  Period.  It won’t matter how technically superior your software is or what functionality it provides, if your users don’t like it they simply won’t use it.  Don’t underestimate the value of user interface design nor of usability.