When reporting service is set up there are two default databases created which are
Reportserver database contains a wide range of information which is briefly listed below.
3. Data sources
7. Notifications and much much more.
I would suggest looking at the tables which are contained in the ReportServer database to get a good understanding about all the data which is stored and within and I have listed below.
I would always recommend setting a maintenance plan to regularly backup this database due to all the important data that is held within. Do not attempt to try and modify the table structure within these tables as you will likely cause an error.
ReportServerTempDB stores temporary data from the ReportServer DB which includes cached reports, session information….. This data is still important and it should still be backed up to aid speedy recovery.