Visibility of system status
The system should always keep users informed about what is going on
and where they are at, 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,
pages, or actions mean the same thing. Follow uniform and/or platform
conventions.
Error prevention
Even better than good error messages is a careful design that prevents
a problem from occurring in the first place.
Recognition rather than recall
Make 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. Give users alternative ways of doing things.
Aesthetic and minimalist design
Dialogues should not contain information that 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.
Affordances
Does the user understand what the text/graphic will do before they activate
it?
Use chunking and Inverted Pyramid
Write material so that documents are short and focused. Do not force
the user to access multiple documents to complete topic. Make text easy
to scan and organize information as inverted pyramid with key points
appearing before more specific detail. Encourage the user to delve as
deeply as needed, but to stop whenever sufficient information has been
received.
Don't lie to the user
Eliminate erroneous or misleading links. Do not refer to missing
information.