ODBC, Open Database Communication, a standard API (application program interface) developed by Microsoft for Windows applications to communicate with database management servers.

If you want to access a database server through an ODBC driver from an application program, you need to meet the following requirements:

* An ODBC driver specifically designed for the database server.

* An ODBC DSN (Data Source Name) - an ODBC configuration representing the ODBC driver and database server.

* An ODBC API (Application Programming Interface) for your application program to interact with database server through the ODBC driver.

For example, if you want to a SQL Server in a PHP script through an ODBC driver, you need to make sure that:

* An ODBC driver for MS SQL Server - The ODBC driver is installed as part of the Windows system.

* An ODBC DSN - You need to create one yourself using the ODBC configuration tool.

* An ODBC API in PHP language - The API is installed as part of the PHP engine.