The Process module defines functions for working with processes to handle things like introspection, starting/stopping, linking, etc.. These are a few that I find to be particularly useful:
Process.list/0- gets a list of all running processes on the BEAM VM.
Process.info/1- accepts a pid as an argument a returns metadata about the process.
Process.alive?/1- accepts a pid as an argument and returns a boolean based on if the process is alive or dead.
Process.exit/2- accepts a pid and an instruction atom (often :kill) and terminates the process
For other process behavior like creating new processes, linking processes and sending messages I find it more useful to use the
More Elixir process posts: Processes for web programmers, Let it crash explained, Processes in phoenix, Processes and concurrency