An initial list of 10 topics are displayed. After you chose one, a new classification of 10 topics is presented. But the original list remains on the screen. After a second choice, a third sub-classification is displayed, along with retaining the first two lists. This continues on with each further selection until there are 4 or 5 lists displayed from left to right.
Further selections create a list on the right with the oldest list removed from the left.
This allows one to easily see the path taken by their decisions-indeed this is the concept of a decision tree applied to the Internet. It is my understanding that all the information has been manually collected. Therefore, this is not truly a search engine. Nevertheless, it contains in excess of 100,000 prime web sites-something to keep you busy for a while. A highly rated site for students, parents and teachers.