As discussed briefly in the first chapter, Mach ports are the fundamental services and primitives of the macOS kernel and are based on Mach 3.0 which was originally conceived as a simple, extensible, communications microkernel.
It is capable of running as a stand-alone kernel, with other traditional operating system services like I/O, file systems, and networking stacks running as user-mode servers.
These are conceptually similar to Unix pipes, sockets, or message queues. Mach ports are lightweight and powerful, ...
