Initialization File: Contains parameters that specify the database block size, the amount of memory to use for the Shared Global Area (SGA), and that control other aspects of how the database instance operates.
Control File: Keeps track of all the files that make up a database.
Redo Log Member: Stores a log of all changes made to the database, the redo log, that is used in the event that the database needs to be recovered.
Tablespace: Tablespaces are logical storage structures that contain table and index data. Oracle allows you to map a tablespace onto one or more physical files.
Datafiles: These are the files that hold the data for tables and for indexes. They are the reason all the other files exist.
Redo Log Group: A group of one or more redo log files that Oracle treats as one. Oracle writes the same information to each file in a group.
Archive Log Destination: This is the location to which Oracle copies redo log files when they are filled.