A file-per-table tablespace is a single-table tablespace that is
created in its own data file rather than in the system tablespace.
Tables are created in file-per-table tablespaces when the
innodb_file_per_table option is
InnoDB tables are created
in the system tablespace. Each file-per-table tablespace is
represented by a single
.ibd data file, which
is created in the database directory by default.
File per-table tablespaces support
COMPRESSED row formats which support features
such as off-page storage for variable length data and table
compression. For information about these features, and about other
advantages of file-per-table tablespaces, see
Section 15.7.4, “InnoDB File-Per-Table Tablespaces”.