Messages are associated with intents that the application generates. At each level of a scenario, you can access messages through the message icon in the action bar.
The Message editor can give you a global view of all the messages associated with a scenario and you can dive into editing them.
An intent can be associated with multiple messages as we typically want to customize messages to specific users. For example, we could have different messages for logged-in users and logged-out users. We can define what message is shown through conditions.
We support a range of message types and are adding more and more UI widgets to make it as simple as possible to create them. You can find a full list of supported messages through "Custom Message" and an explanation of the underlying XML structure here.