PDO is a highly performant and actively maintained database extension that has a unique advantage over vendor-specific extensions. It has a common Application Programming Interface (API) that is compatible with almost a dozen different Relational Database Management Systems (RDBMS). Learning how to use this extension will save you hours of time trying to master the command subsets of the equivalent individual vendor-specific database extensions.
PDO is subdivided into four main classes, as summarized in the following table: