Ruby virtual machines. MRI is the VM for ruby 1.8 (Matz ruby implementation and Matz is the creator of ruby), YARV is the newer incanation that was developed fo

Ruby virtual machines. MRI is the VM for ruby 1.8 (Matz ruby implementation and Matz is the creator of ruby), YARV is the newer incanation that was developed for ruby 1.9 these are all written in C. There plenty of other ruby VMs like rubinius or jruby etc.