How do you know it's easy to use?

There are lots of gadgets and lots of programs out there that are totally unusable. Whoever designed them didn't worry about people at all. They assumed that we would learn the manual cover to cover and do the right thing - and if they found it hard they must just be thick!. After all the designer doesn't have a problem using it!

Mostly it's not that bad, but it is hard for someone who designs a gadget to put themselves in the position of other people who know nothing about it. What is needed are ways to evaluate the device - not for whether it works but for whether it is easy to use. That is where usability evaluation methods come in ...