User-Mode Linux lets you run Linux inside Linux. It is a safe, secure way of running Linux versions and Linux processes. Run buggy software, experiment with new Linux kernels or distributions, and poke around in the internals of Linux, all without risking your main Linux setup. User-Mode Linux gives you a virtual machine that may have more hardware and software virtual resources than your actual, physical computer. You can assign your virtual machine only the hardware access you want it to have. With properly limited access, nothing you do on the virtual machine can change or damage your real computer or its software.
