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.
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.
Excerpted from Jakob Nielsen's Ten Usability Heuristics
for Human Computer Interactions.
As someone who develops computer-user interfaces, I have a professional and ethical responsibility to design systems that users can use successfully.
Sure there's money to be made by doing it well, but the money is simply an artifact that flows from customer satisfaction. In my business, when you don't look after the customer they feel like idiots because they can't figure out how the web site works. If they can't finish the thing they set out to do they hate themselves and they hate you and they leave before they're done.
It's true that there are folks in my profession who blame the user for not being able to figure things out. Fortunately this philosophy is growing increasingly unfashionable.
I am responsible for seeing that my user doesn't leave for any of the wrong reasons. If I blow it, my client loses a sale. If I continue to blow it I will lose my job.
The stakes are higher in Vancouver, where a poorly designed, high velocity luge run led to the death of Olympic athlete Nodar Kumaritashvili on Friday.
It's bad enough that there was an opportunity for Kumaritashvili to fly off the course; worse that there were steel poles in close proximity to the icy run where lugers customarily reach speeds exceeding 90 miles per hour.
It is reprehensible that the Vancouver Olympic Committee and International Luge Federation would issue a statement which, in effect, blamed the accident on user error:
It appears after a routine run, the athlete came late out of curve 15 and did not compensate properly to make correct entrance into curve 16. This resulted in a late entrance into curve 16 and although the athlete worked to correct the problem he eventually lost control of the sled resulting in the tragic accident. The technical officials of the FIL were able to retrace the path of the athlete and concluded there was no indication that the accident was caused by deficiencies in the track.
How wrong? See the responsibilities inherent in: User Control & Freedom along with Error Prevention, above.