The book To Become an Oracle DBA in Eighty Days explains the concepts of oracle database using the stories from Jules Verne's novel Around the World in 80 Days:
One Oracle Database Architecture
Two Oracle Network Configuration
2.1. Client Request
2.2. Network Configuration Files
2.3. Listener Static and Dynamic Register
2.4. Listener Failover and Load Balance
Three Database Grid Control
3.1. Grid Control Structure
3.2. Event and Notification
3.3. Scheduled Job
Four Backup, Recovery and RMAN
4.1. System Change Number (SCN)
4.2. Online Backup
4.3. Recovery
4.4. Oracle Recovery Manager (RMAN)