Before you begin this chapter, you should understand the basics of InnoDB.
As per the MySQL documentation,
System Tablespace (Shared tablespace)
"The InnoDB system tablespace contains the InnoDB data dictionary (metadata for InnoDB-related objects) and is the storage area for the doublewrite buffer, the change buffer, and undo logs. The system tablespace also contains table and index data for any user-created tables that are created in the system tablespace. The system tablespace is considered a shared tablespace since it is shared by multiple tables.
The system tablespace is represented by one or more data files. By default, one system data file, named ibdata1, is created in the MySQL data directory. The size and number of system ...