The Microsoft Data Access Components (MDAC) are a framework from Microsoft for accessing databases. As you can read in the Software Maintenance blog, you can run into a lot of MDAC pain during installation.

MDAC consists of three major components:
1. ADO

The last version of the MDAC released by Microsoft was 2.8. To be more precise it was 2.8 SP 1. Since then, the MDAC functionality has been built into Microsoft Windows 98, XP, 2000, and Me.

Microsoft provides a redistributable installer for the MDAC. You can check the version of the MDAC on your system with the Microsoft Component Checker tool. You can also look in the Windows registry to find the MDAC version number. However this is not as reliable as the Component Checker.