MyISAM was the default storage engine for MySQLprior to 5.5 1. MyISAM storage engine tables do not support ACID-compliant as opposed to InnoDB. MyISAM tables support table level locking only, so MyISAM tables are not transaction-safe. MyISAM tables are optimized for compression and speed. MyISAM is generally used when you need to have primarily read operations with minimal transaction data. The maximum size of a MyISAM table can grow up to 256 TB, which helps in use cases like data analytics.