Ten Usability Heuristics by Jakob Nielsen
http://www.useit.com/papers/heuristic/heuristic_list.html
1. Visibility of system status
The system should always keep users informed about what is going on, through appropriate feedback
within reasonable time.
2. 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.
3. 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.
4. Consistency and standards
Users should not have to wonder whether different words, situations, or actions mean the same thing.
Follow platform conventions.
5. Error prevention
Even better than good error messages is a careful design which prevents a problem from occurring in
the first place.
6. 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.
7. 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.
8. 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.
9. 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.
10. 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.