This driver should be used for the MySQL database and all derivitives, such as MariaDB and Percona. It supports all table types. It uses the MySQL Improved Extension. From PHP version 5.3, this is the recommended driver for MySQL connections. The support for this driver is built in to PHP

This driver only supports non-transactional connections and is based around the now deprecated Original MySQL driver.

This driver extends the mysql driver and supports transactional connections to innodb table types.

This driver adds an undocumented layer of portablity to the deprecated mysqlt driver.