Default storage engine in mysql
Before MySQL 5.5.5, MyISAM is the default storage engine. (The default was changed to InnoDB in MySQL 5.5.5.) MyISAM is based on the older (and no longer available) ISAM storage engine but has many useful extensions.
Each MyISAM table is stored on disk in three files. The files have names that begin with the table name and have an extension to indicate the file type. An .frm file stores the table format. The data file has an .MYD (MYData) extension. The index file has an .MYI (MYIndex) extension.
As of MySQL 5.5.5, it is normally necessary to use ENGINE to specify the MyISAM storage engine because InnoDBis the default engine. Before 5.5.5, this is unnecessary because MyISAM is the default engine unless the default has been changed. To ensure that MyISAM is used in situations where the default might have been changed, include the ENGINE option explicitly.