This is a nicely written introduction, with non-intimidating language. It has links to places for further detail so that one can browse at different levels of detail (the dream of the hyper linked web!), though in some cases it would be even nicer if the author (or someone) could write a short paragraph about the sub-topic.
As an example, when talking about growing a decision tree, Information is mentioned. The link goes to the wikipedia page for Information theory, which is vast, but perhaps more helpful here would be a statement like
“New paths are added by calculating how much new information they would add. In this case, information is a measure of how much reduction in uncertainty in the potential category of the input we achieve by adding the path/branch. If, for example, by adding the branch we reduce the number of potential categories from 10 to 5, this is much more information that a branch that reduces 10 to 8, and we would chose the first branch to grow our tree. For a formal definition of Information and notes on information theory please see <the wikipedia link>”
The page was very informative for me, thanks!