Short for "Metamodel On A Runtime", MoarVM is a modern virtual machine built for the Rakudo compiler implementing the Raku Programming Language, and the NQP Compiler Toolchain. MoarVM is used by the majority of Raku programmers. Highlights include:

Great Unicode support, with strings represented at grapheme level
Dynamic analysis of running code to identify hot functions and loops, and perform a range of optimizations, including type specialization and inlining
Support for threads, a range of concurrency control constructs, and asynchronous sockets, timers, processes, and more
Generational, parallel, garbage collection
Support for numerous language features, including first class functions, exceptions, continuations, runtime loading of code, big integers and interfacing with native libraries