This document specifies the implementation of PDO, PHP Data Objects, both from the perspective of PHP script level APIs used by people developing PHP applications, and from the perspective of C level APIs in the PDO internals that will be used by people developing PDO drivers. Briefly summarize the chapters here. Acknowledgments A number of people were involved in the development of PDO and its drivers; without them it wouldn't be what it is, and you wouldn't be reading this text. Those people are: Ilia Alshanetsky, Ard Biesheuvel, Marcus Börger, Sara Golemon, Sterling Hughes, Edin Kadribašić Frank Kroman and George Schlossnagle from the PHP community, Chris Jones from Oracle, Dan Scott, Bill Abt, Kellen Bombardier Rick McGuire and Krishna Raman from IBM.