Physical Structures

Datafiles
Every Oracle database has one or more physical datafiles.
The datafiles contain all the database data. Tables and indexes are also stored in the datafiles.

Control Files
Every Oracle database has a control file. 
it contains Database name, Names and locations of datafiles and redo log files, Time stamp of database creation

Redo Log Files
Every Oracle database has a set of two or more redo log files. The primary function of the redo log is to record all changes made to data.

Overview of Schemas and Common Schema Objects

A schema  is a collection of database objects. A schema is owned by a database user and has the same name as that user.

Schema objects  include structures like tables, views, and indexes. (There is no relationship between a tablespace and a schema. Objects in the same schema can be in different tablespaces, and a tablespace can hold objects from different schemas.)

Tables  are the basic unit of data storage in an Oracle database. Database tables hold all user-accessible data.

Indexes  are optional structures associated with tables. Indexes can be created to increase the performance of data retrieval.

Views  are customized presentations of data in one or more tables or other views. A view can also be considered a stored query. Views do not actually contain data.
The primary function of views is that They hide data complexity and store complex queries.