What data is usually stored in a database for an application that implements synchronous interaction between the client and the server?

In an application with synchronous interaction between the client and server, the database usually stores the following data:

• User data — information about users, their profiles, settings.
• Session or transaction states — to track the current status of interactions.
• Request and response logs — for debugging and auditing.
• Cached data — to speed up repeated requests.
• Synchronization data — for example, timestamps or data versions to determine what changes need to be transmitted.

This storage ensures data consistency between the client and server, as well as restoring the state in case of failures or reconnections.