Jikes RVM (Research Virtual Machine) is a flexible open testbed to prototype virtual machine technologies and experiment with a large variety of design alternatives. It differs from other Java virtual machine projects in that it is written in Java whilst having a full adaptive optimization framework. It is a vehicle for testing a wide range of ideas including compiler research, memory management research, Java runtime systems, computer architecture, and aspect oriented programming to name a few. It is widely used for research and teaching; for example, over 200 research papers have been published which use Jikes RVM.