As a Java-programmer you'll probably find it easy to work with objects. To create an instance of a class one can simply use "new" and maybe a couple of setter-methods. To save your instances, so you can continue working with them tomorrow might be trickier. One solution would be to serialize your objects and store them in XML format in a flat file. If you've got many objects with complex relations then you'll soon find out that this is not the way to go. If you've got a database system and you know your SQL, then you have a solution that works. On the other hand: what if you could simply say "save my objects", and they'd be in your data base? That'd be nice, right?