The ODBC Oracle driver.
Access to databases is managed by the Microsoft ODBC Driver Manager. The driver manager provides the linkage between an ODBC application and an ODBC driver for a specific database management system.
The Oracle ODBC driver configuration has changed slightly with each newer version of the ODBC driver, but there are only 2 pieces of information that are absolutely required to create a working Oracle DSN:
When you have multiple oracle software installed (such as the Oracle Database and Oracle Warehouse Builder, pay attention that the path of the database bin repository must be the first one in the PATH environment variable otherwise you can have this error:
[Microsoft][ODBC Driver Manager] Driver's SQLAllocHandle on SQL_HANDLE_ENV fail