Rules are used to issue HTTP requests to remote servers when a pre-defined condition is triggered. For example, this can be used to define alarms which generates HTTP requests to a remote SMS service when a temperature resource is above 20 degrees. This makes it possible to send an SMS indicating an alarm situation.
Rules are defined from the configuration menu in Managed IoT Cloud. You will find rules under the settings -> rules menu.
Follow the on screen guide to create a rule.