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1.6 More on usability: design and usability principles 27

an evaluation. Below are the ten main usability principles, developed by Nielsen
(2001) and his colleagues. Note how some of them overlap with the design principles.
1. Visibility of system status-always keep users informed about what is going
on, through providing appropriate feedback within reasonable time
2. Match between system and the real world-speak the users' language, using
words, phrases and concepts familiar to the user, rather than system-
oriented terms
3. User control and freedom-provide ways of allowing users to easily escape
from places they unexpectedly find themselves, by using clearly marked
'emergency exits'
4. Consistency and standards-avoid making users wonder whether different
words, situations, or actions mean the same thing
5. Help users recognize, diagnose, and recover from errors-use plain lan-
guage to describe the nature of the problem and suggest a way of solving it
6. error prevention-where possible prevent errors occurring in the first place
7. Recognition rather than recall-make objects, actions, and options visible
8. Flexibility and efficiency of use-provide accelerators that are invisible to
novice users, but allow more experienced users to carry out tasks more
quickly
9. Aesthetic and minimalist design-avoid using information that is irrelevant
or rarely needed
10. Help and documentation-provide information that can be easily searched
and provides help in a set of concrete steps that can easily be followed

One of the main design principles which Nielsen has proselytized, especially for website de-
sign, is simplicity. He proposes that designers go through all of their design elements and re-
move them one by one. If a design works just as well without an element, then remove it. Do
you think this is a good design principle? If you have your own website, try doing this and
seeing what happens. At what point does the interaction break down?

Comment Simplicity is certainly an important design principle. Many designers try to cram too much into
a screenful of space, making it unwieldy for people to find what they are interested in. Remov-
ing design elements to see what can be discarded without affecting the overall function of the
website can be a salutary lesson. Unnecessary icons, buttons, boxes, lines, graphics, shading,
and text can be stripped, leaving a cleaner, crisper, and easier-to-navigate website. However, a
certain amount of graphics, shading, coloring, and formatting can make a site aesthetically
pleasing and enjoyable to use. Plain vanilla sites with just lists of text and a few hyperlinks may
not be as appealing and may put certain visitors off returning. The key is getting the right bal-
ance between aesthetic appeal and the right amount and kind of information per page.

Design and usability principles have also been operationalized into even more spe-
cific prescriptions called rules. These are guidelines that should be followed. An ex-
ample is "always place the quit or exit button at the bottom of the first menu list in
an application."