High Quality Content by WIKIPEDIA articles! Microsoft`s ActiveX Data Objects (ADO) is a set of Component Object Model (COM) objects for accessing data sources. A part of MDAC, it provides a middleware layer between programming languages and OLE DB (a means of accessing data stores, whether they be databases or otherwise, in a uniform manner). ADO allows a developer to write programs that access data without knowing how the database is implemented. He must be aware of the database for connection only. No knowledge of SQL is required to access a database when using ADO, although one can use ADO to directly execute SQL commands. The disadvantage of the latter is that it introduces a dependency upon the type of database used.