Clicking on a link is just like flipping to the next page in a book. Not everyone uses the same system software, and we don't all use the same web browser. What I see on my computer won't necessarily be the same that Dr. James or any of my classmates will see. Having your ideas and information available to everyone in the world has never been so easy. Instead of having to spend 35 dollars for a famous person's autobiography, I could type in their URL and learn about what they eat for breakfast at little or no charge.
Many people know how to go to a library and search for a book that they are looking for.
On the Internet, it's very similar. If a website is poorly designed or their is no navigation table like Dr. James has taught us to make, a visitor can easily get lost. Making sure you have some kind of navigation table or index will reduce the probability of your visitor getting lost. The more complex a webpage gets, the more important it is to have good navigation. He has researched different web sites and gathered feedback from internet users.