Every table has a format file in its database directory. The format file is created by the server and contains the definition, or structure, of the table. The format filename is the save as the table name, plus an .frm suffix.

The MyISAM engine creates a data file (.MYD) and index file (.MYI) for each table.

By default, the InnoDB engine shares files for multiple tables. If Country is an InnoDB table, there will e a Country.frm format file but the InnoDB engine stores the table data and index information in the InnoDB shared table space. (InnoDB table space is shared among all databases.)

The MEMORY engine does not use any disk storage.