V8 Engine comes with two compilers, one of which is full-codegen which produces simple machine code. The second one is crankshaft compiler which is a complex compiler that produces optimized code. There are different types of threads present in V8 Engine internally. The main thread fetches code, compiles it and executes it. There are other threads for compiling so that the main thread can optimize in the meantime. There is also a profile threat whose job is to detect the methods that are likely to spend a lot of time so that Crankshaft can optimize them. Besides, there are some garbage collecting threads.
Since it is developed in C++, one can embed it into any C++ application. More than Chrome, V8 Engine is more popular in the world for its application in Node.js runtime environment.