Short for Data Source Name. Data Source Name provides connectivity to a database through an ODBC driver. The DSN contains database name, directory, database driver, UserID, password, and other information. Once you create a DSN for a particular database, you can use the DSN in an application to call information from the database.
There are three types of DSNs:
(1) System DSN -- can be used by anyone who has access to the machine. DSN info is stored in the registry.
(2) User DSN -- created for a specific user. Also stored in the registry.
(3) File DSN -- DSN info is stored in a text file with .DSN extension.
There is also what is known as a "DSN-less connection." Instead of using a DSN to connect to a database, the developer specifies the necessary information right in the application. With a DSN-less connection the developer is free to use connection standards other than ODBC, such as OLE DB.