It consists of one or more data files, control files, two or more redo log files.
The Database contains multiple users/schemas one or more rollback segments, tablespaces, Data dictionary tables, User objects (table ,indexes,views etc.,)
The server that access the database consists of SGA (Database buffer, Dictionary Cache Buffers, Redo log buffers, Shared SQL pool), SMON (System MONito), PMON (Process MONitor), LGWR (LoG Write), DBWR (Data Base Write), ARCH (ARCHiver), CKPT (Check Point), RECO Dispatcher, User Process with associated PGS
