The PhysBeans library is an open source project distributed under the GPL license. This means that you can copy, modify and redistribute the library and all applets created with it, but you have to respect the copyright of the authors. If you only want to use the applets, you just need applets.zip. To create your own applets, download the PhysBeans jar file and the NetBeans integration. The PhysBeans sources are only necessary if you want to create your own beans based on PhysBeans. The applet sources may serve as examples how to use PhysBeans or as starting points for own modifications.