.. note::

   Difference between **registration** of widgets and **implementation** of widgets:

   Widgets provide some functionality, e.g. collect system log errors over a time span.
   This functionality is provided by the implementation, a PHP class with some code.
   The registration is done in :file:`Services.yaml`,
   in order to create the actual widget with provided functionality.
   During registration options can be set, e.g.  the time span.

   Registration is documented at :ref:`register-new-widget`,
   while implementation is documented at
   :ref:`implement-new-widget`.
