Magnolia 5.4 reached end of life on November 15, 2018. This branch is no longer supported, see End-of-life policy.
Action is an instruction to invoke an event in the user interface. You typically execute an action by clicking it in the action bar or in a dialog. For example, saving a dialog is an action. Most actions take place in the user interface only - they don't interact with external logic. However, an action can do more complex things such as execute a command.