     * `os_time/0` - the time reported by the OS. This time may be
       adjusted forwards or backwards in time with no limitation;
 
-    * `system_time/0` - the VM view of the `os_time/0`. They may
-      not match in case of time warps although the VM works towards
-      aligning them. This time is not monotonic (i.e. it may decrease)
+    * `system_time/0` - the VM view of the `os_time/0`. The system time and OS
+      time may not match in case of time warps although the VM works towards
+      aligning them. This time is not monotonic (i.e., it may decrease)
       as its behaviour is configured [by the VM time warp
       mode](http://erlang.org/doc/apps/erts/time_correction.html#Time_Warp_Modes);
 
     * `monotonic_time/0` - a monotonically increasing time provided
-      by the Erlang VM
-
-  The time functions in this module works in the `:native` unit,
-  which is OS dependent. Most of the time, all calculations are
-  done in the `:native` unit, to avoid loss of precision, with
-  `convert_time_unit/3` being invoked at the end to convert to
-  milli, micro or nanoseconds. See the `t:time_unit/0` type for
+      by the Erlang VM.
+
+  The time functions in this module work in the `:native` unit
+  (unless specified otherwise), which is OS dependent. Most of
+  the time, all calculations are done in the `:native` unit, to
+  avoid loss of precision, with `convert_time_unit/3` being
+  invoked at the end to convert to a specific time unit like
+  milliseconds or microseconds. See the `t:time_unit/0` type for
   more information.
 
   For a more complete rundown on the VM support for different

  """
  @spec system_time(time_unit) :: integer
  def system_time(unit) do
    :erlang.system_time(convert_time_unit(unit))
  end

  @doc """

defmodule System do
  @moduledoc """
  The `System` module provides functions that interact directly
  with the VM or the host system.

  ## Time

  The `System` module also provides functions that work with time,
  returning different times kept by the system with support for
  different time units.

  One of the complexities in relying on system times is that they
  may be adjusted. For example, when you enter and leave daylight
  saving time, the system clock will be adjusted, often adding
  or removing one hour. We call such changes "time warps". In
  order to understand how such changes may be harmful, imagine
