DAO is the programmatic interface between VBA and Access database engine databases, ODBC (Open Database Connectivity) data stores, and installable ISAM (Indexed Sequential Access Method) data sources, such as Excel, Paradox, dBase, and Lotus 1-2-3.DAO was first released as a part of Visual Basic 2.0 and later released with Access 1.0 in November 1992. Over the years, many changes have been made to both DAO and to the Microsoft Jet database engine to reflect technologies at the time. Support for 32-bit operating systems, ODBC data sources, and Unicode languages were all included in current versions of DAO.
DAO 12.0 is the latest version, shipped with Access 2007, and is the version used by the new ACCDB file format. This new release was written for use with the Access database engine, which is an updated version of the Microsoft Jet database engine and is 100% compatible with Jet. The new features added to DAO and the Access database engine include new objects and properties that support multi-value lookup fields, a new Attachment data type, append-only memo fields, and database encryption using the database password. The filename for the Access database engine is ACECORE.DLL. (With ACE in the name, you may occasionally see the Access database engine referred to as ACE in newsgroups and blogs.)