A case (also known as a ticket) is something that allows you to track constituent's concern, and manage it by way of categorizing, assigning, and setting up follow-up reminders respectively. 

For example

A constituent called your office complaining about waste bins that have not been picked up in two weeks!

This is something you need to:

• Log the call
• Record the notes of the conversation
  
• Track that it was related to waste management
• Assign it to the right staff member
• Set follow up reminders so it doesn't fall through cracks
• Track each action taken to resolve the matter

Case tickets will allow you to do all of that!