ODBC connections allows a Windows computer to connect to a data source. Typically the datasource is a database. In a 32-bit version of windows, you just create the ODBC connection and it works. In a 64-bit version of windows, then it is more complex.
In a 64-bit version of Windows, you need to create an ODBC connector to that matches the application. For a 64-bit application, you create a 64-bit ODBC connection. For a 32-bit app, you create a 32-bit ODBC connection.
The most common problem is creating an ODBC connection by using the ODBC Data Source Administrator tool in control panel and then you are unable to see of view the ODBC connection from a 32-bit application. The ODBC Data Source Administrator tool that you can open from control panel creates only 64-bit ODBC connections. To create 32-bit ODBC connections you need to run Odbcad32.exe from the C:\Windows\SysWoW64 folder.