I find that developers, designers, and people that do the easy stuff in businesses (marketing, project management) have trouble understanding what usability is.
I was watching a panel discussion the other day, and saw a great example of what usability is — Soda (or Pop, or Coke depending on where you grew up).
The story: you are handed a soda that you have not tried before. You are in a meeting, with some really important things going on, but you are thirsty. While listening to the meeting, you get ready to pop the top on the can, and take a sip.
What could happen next is a great usability lesson.
The can doesn’t make a huge noise when you open it, and the cold liquid is in your mouth in no time. Impressed by the taste, you take another sip, and then look at the label to find out more. You want to know a few key things, such as name, sugar content and where it comes from (all are located in different sections of the can). Wow, who ever knew that Diet Rasberry Cheesecake Dr. Pib would ever taste so good, and there isn’t too much sugar which is a huge bonus. To kick it off, the water is pure Mt. Everest runoff (how cool). The caffeine gives you a kick so you can pay attention and catch details of the meeting. You finish the can and toss it in the recycling bin, off to do some great things.
That is good usability. You were able to open the can, drink it, enjoy it and find out the info you wanted to know. You would buy it if you saw it in a store.
You are handed a can of soda in the meeting. Trying to open it, you break a nail. You have to ask another person in the meeting to open it, causing an embarrassing disturbance. You try it, and if were not so thirsty would not take another sip because of the horrid taste, but you are really thirsty so you drink most of the can. The side of the can is sticky. You try to read the label to see what it is, but the green on black logo is not readable. The caffeine is a lot more than you thought and you start jittering. The meeting flies by as you develop a stomach ache.
That is horrid usability. The product, at almost every level, sucked for you (but you needed it, so you used it).
This of websites that this applies to. MySpace, Twitter, Facebook, Hotmail. They all have a good soda vs. bad soda usability case, depending on how you use them. My grandma uses and loves hotmail, it is a good soda for her. Hotmail is full of ads, buggy and slow, not a good soda for me. Everyone is different.