There is a possibility that our logic ends up in a network error or some unexpected exception. Imagine a scenario where our service needs to call a particular database instance to fetch some data. We might face connection timed out or some other similar errors. In that case, what should be our behavior? Maybe trying to establish the connection a couple of times will help, this can be achieved if our tasks are performed in such a hierarchical manner. We can achieve this task by performing hierarchy via the actors in place. And if some actor from down in the hierarchy fails and can communicate the failure to parent actor, the parent actor, based on the type of failure, can restart/kill the actor or perform some other operation as required. This is in a sense supervising the actors below in the hierarchy; let's say parent actors can supervise...