In the following example, the greet function inside Greeter module is run in a separate process:
defmodule Greeter do
    def greet do
        IO.puts "Hello programmer!"
    end
end
iex> spawn(Greeter, :greet, []) 
Hello
#PID<0.122.0>
Here #PID<0.122.0> is the process identifier for the spawned process.