ODBC driver managers
The driver manager is the ODBC component that manages communication between applications and ODBC drivers. In most cases, ODBC applications issue ODBC API calls to the driver manager, and the driver manager, in turn, passes those calls to the appropriate ODBC driver. The ODBC driver then accesses the underlying database management system software.
For performance reasons, depending on the database management system software, some API functions might bypass the driver manager and access the ODBC driver directly.