Cases provide an issue tracking ability. It's a principal aspect of customer service in EspoCRM. Ticket term also can be used for Cases.
Case entity can be associated with one Account and/or with multiple Contacts.
New cases are supposed to be created by the following scenarios:
Case record has a stream that can be utilized for a communication between customer and service. CRM users can also make internal posts that won't be visible in a customer portal.
When the new case is created by a portal user it's not assigned to any user. By utilizing Workflows administrator can create rule that will notify certain users about a new case in the system. Workflows also provide an ability to apply assignment rule to new cases, i.e. Round-Robin and Least-Busy rules. For more complex business flows it's recommended to utilize BPM tool.
To prevent overlooking of new cases, users can add Case entity type to the Global Auto-follow list at Preferences. Then they will automatically follow every new case.
Note: If there is no portal user associated with a linked contact, then the customer won't receive email notifications about updates in the Stream. You need to use emails for communication with the customer.
Administrator can set up Group Email Account that will create a new case on each new inbound email. For more information see here.
Users can relate knowledge base articles to the case record.
Administrator can create a portal where customers will be able to create cases.
Since portal users automatically follow their cases, they will receive email notifications about new messages in the Stream.