Communication Templates allow the designer to create and modify templates which can be used in place of default system emails, and used as the input to some inbuilt Actions and Escalations (primarily Send Email).
Templates can be managed via the "Communication Templates" link on the left-hand navigation menu in Manage:
By default, the Communication Templates page displays the existing System Templates, which can be modified to change the content that will be emailed to users at the relevant time (for example the Password Reset process). These templates cannot be deleted or renamed.
The "New Communication Template" button allows a designer to create a template which can be used with the Send Email action and escalation.
Both System and Custom templates can have translations added for multiple languages - these will be substituted as appropriate according to the language defined in the user's profile.
See the API Reference for details.
Once defined in Manage, Custom communication templates can be used in Design, where supported by an Action. For example, the Send Email action can have its Email Body input drawn from a Communication Template: