Node.js is not a language. It is a runtime environment for Javascript, much like web browsers are. Both node.js and web browsers use V8, which is a javascript "engine", which means it's the part of the code that parses and executes Javascript code. V8 happens to use a JIT execution model. Node itself is not specific to V8 (anymore) and can embed on other JS engines as well, including engines that are pure interpreters, like most were before V8, although all popular engines in use today use JIT compilation.