DAO, COM, and the Microsoft Jet Database Engine

One feature of DAO is a set of COM interfaces, which, like all COM interfaces, are nothing more than specifications—sets of pure virtual function declarations. These interfaces have names such as DAOWorkspace, DAODatabase, and DAORecordset. (Notice that these interface names don't begin with the letter I as do most other interface names.)

The other feature of DAO is the implementation of those interfaces. Microsoft supplies the COM module DAO350.DLL, which connects to the same Jet database engine DLL that serves the Microsoft Access database product. As a Visual C++ developer, you have royalty-free redistribution rights to these DLLs. At the moment, the only DAO implementation available with Jet is DAO350.DLL, but nothing prevents other database software companies from providing their own DAO implementations.