The full form of ADO is Active Data Object

In computing, Microsoft’s ActiveX Data Objects (ADO) comprises a set of Component Object Model (COM) objects for accessing data sources. A part of MDAC (Microsoft Data Access Components), it provides a middleware layer between programming languages and OLE DB (a means of accessing data stores, whether databases or not, in a uniform manner). ADO allows a developer to write programs that access data without knowing how the database is implemented; developers 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 execute SQL commands directly (with the disadvantage of introducing a dependency upon the type of database used).

ActiveX Data Objects is a programming model, which means that it is not dependent upon any given back-end engine. Currently, however, the only engine supporting the ADO model is OLE-DB. There are many native OLE-DB Providers as well as an OLE-DB Provider for ODBC. ADO is used in C++ and Visual Basic programs to connect to SQL Server and other databases. Of course, it also works to connect to Azure SQL Database in the cloud.

Microsoft ActiveX Data Objects (ADO) enable your client applications to access and manipulate data from a variety of sources through an OLE DB provider. Its primary benefits are ease of use, high speed, low memory overhead, and a small disk footprint. ADO supports key features for building client/server and Web-based applications.