It continues to amaze me how many great, free, open source Java tools are out there. When I needed a lightweight object/relational mapping service for a JSP e-commerce project several years ago, I had to build my own. It evolved over the years , developed some cool and unique features, and we've used it in a wide variety of different contexts. But now that I've discovered Hibernate, I expect that I'll be using it on my next project instead of my own familiar system (toward which I'll cheerfully admit bias). That should tell you how compelling it is!
Since you're looking at this book, you're interested in a powerful and convenient way to bridge between the worlds of Java objects and relational databases. Hibernate fills that role very nicely , without being so big and complicated that learning it becomes a daunting challenge in itself. To demonstrate that, this chapter guides you to the point where you can play with Hibernate and see for yourself why it's so exciting.