Visibility of system
status
The system should always keep users informed about what is going
on, through appropriate feedback within reasonable time.
Match between system
and the real world
The system should speak the users' language, with words, phrases
and concepts familiar to the user, rather than system-oriented terms. Follow
real-world conventions, making information appear in a natural and logical
order.
User control and
freedom
Users often choose system functions by mistake and will need a
clearly marked "emergency exit" to leave the unwanted state without
having to go through an extended dialogue. Support undo and redo.
Consistency and
standards
Users should not have to wonder whether different words,
situations, or actions mean the same thing. Follow platform conventions.
Error prevention
Even better than good error messages is a careful design which
prevents a problem from occurring in the first place. Either eliminate
error-prone conditions or check for them and present users with a confirmation
option before they commit to the action.
Recognition rather
than recall
Minimize the user's memory load by making objects, actions, and
options visible. The user should not have to remember information from one part
of the dialogue to another. Instructions for use of the system should be
visible or easily retrievable whenever appropriate.
Flexibility and
efficiency of use
Accelerators unseen by the novice user may often speed up
the interaction for the expert user such that the system can cater to both
inexperienced and experienced users. Allow users to tailor frequent actions.
Aesthetic and
minimalist design
Dialogues should not contain information which is irrelevant or
rarely needed. Every extra unit of information in a dialogue competes with the
relevant units of information and diminishes their relative visibility.
Help users recognize,
diagnose, and recover from errors
Error messages should be expressed in plain language (no codes),
precisely indicate the problem, and constructively suggest a solution.
Help and documentation
Even though it is better if the system can be used without
documentation, it may be necessary to provide help and documentation. Any such
information should be easy to search, focused on the user's task, list concrete
steps to be carried out, and not be too large.
