ODBC (Open Database Connectivity) is a set of specifications and APIs developed by Microsoft to enable interoperability among disparate RDBMS by providing a translation layer. For more information about the specifications itself, consult Wikipedia's article on ODBC.

Microsoft Access is ODBC-compliant and is capable of linking to ODBC-compliant data sources as well as using OLEDB within Access Data Project or via ActiveX Data Object Library (ADO). Linked tables created via Access UI are ODBC within context of .mdb and .accdb files. Such tables are known as linked tables.

ODBC Drivers

ODBC APIs requires that the vendor RDBMS, including Access, develop and provide their drivers. A standard Windows installation usually has a set of ODBC drivers installed already, usually for Access, SQL Server, Oracle. If a different vendor RDBMS is used, it may be necessary to download the ODBC driver from their website and install it on all client machines.

ODBC Things to Look out for

Other databases may allow characters (in table field names) which are not allowed in Access e.g. a full stop /period character. When such characters are encountered in the linked table, a normal Access Query (e.g. a Select Query) will not work and an Access 'Pass-Through' query may need to be used.