a DSN, is a way for you to connect to a database merely by referencing the DSN name, and without having to specify the entire path to the database. That’s particularly handy if you have a bunch of scripts that access this database. If you hard-code the path into the scripts and then move the database from one server to another, you’ll have to edit the path on each and every script. If you use a DSN, however, you won’t have to edit the scripts at all; instead, you just need to modify the DSN. That’s one change versus hundreds of changes (depending on how many scripts you have).