Xen is still very much a moving target. It is under active development, and substantial aspects of its architecture are evolving. Many details of Xen are documented only in the code itself. This appendix highlights helpful resources for getting additional information and for tracking the inevitable changes in Xen. We highlight a few of the main sources of good information about Xen; there are of course many others, including excellent articles or blogs from early Xen adopters. As with most topics, your curiosity and a good search engine will take you a long way.