IEx is Elixir’s interactive shell, where you can type any Elixir expressions and get its result. One issue you might come across when trying to use iex in Powershell, through a command e.g. iex -S mix, you might get the following error: [crayon-589dd336d7efc799259712/] The problem is that iex is an alias in Powershell, for Invoke-Expression ...