- ADO is a COM-based library for accessing databases.
- OleDB and ODBC are standards for communicating with databases.
- ADO uses the OleDB to talk to any database that exposes an OleDB driver.
- There is also an OleDB driver that can wrap any ODBC driver. Thus ADO can also talk to any database that exposes an ODBC driver.
- ADO.NET (a.k.a. System.Data) is a .NET based library for accessing databases.
- ADO.NET has built-in support for SQL Server, OleDB, and ODBC
- Third parties can expose their database to ADO.NET by building a ADO.NET compatible library
- Third parties can also expose their database to ADO.NET by offering an OleDB or ODBC driver