Upon assigning a record to a specific user, a task can be created that will inform the user that the assignment has been created.
To begin, click your Username → Settings → Automation
Click Create Rule.
Since the rule will be created based on case assignment, the module we will select will be Cases.
In the WHEN section, select On a record action. The record action will be Edit, since we will be creating the task once the case's owner has been edited.
For the condition, we will want the workflow to run when the owner field is populated.
Click the Click Here button and select [owner]
Change the dropdown to 'not equal to'
Enter a zero in the last textbox.
In the Instant Actions section, select Create for the Action Type.
Select Activity -> New Task from the dropdown.
The task template will appear. This will allow you to create a general task that will be assigned to each user when the workflow rules are met.