Each operating system has its interface for the event demultiplexer and each I/O operation can behave quite differently depending on the type of the resource, even within the same OS. Libuv is a C library that makes Node.js compatible with all the major platforms and normalizes the non-blocking behavior of the different types of resource; libuv today represents the low-level I/O engine of Node.js.
Please refer to the official libuv documentation at https://libuv.org/ and http://docs.libuv.org/en/v1.x/ if you wish to learn more.
