The preceding HTTP module is wired using the net module. According to documentation of the node.js api, the net module provides an asynchronous network API for creating stream-based TCP or IPC servers. This is one of the compiled binary library of core Node, which interacts with the internal C library called libuv. The libuv library is responsible for handling asynchronous request such as I/O and network-related operations. The best documentation to refer is Node's own documentation: https://nodejs.org/api/net.html.