For example, a DVD may be restricted to Asia and hence can't be played on DVD devices in North America.  Some DVD discs don't have a region restriction and can be played on any device around the world.

The Mac OS X DVD Player is limited to playing discs for only one particular region and is most often restricted to where your Mac was purchased.  Note however that DVD Player is capable of playing discs from any region and the change entails a process called a "switch".  DVD Player allows the region to be changed up to five times.  The region setting for the DVD player is stored in the Combo Drive or SuperDrive drive firmware.

If you like to make home movies, DVD Player will play the DVDs you create with Apple's iDVD and DVD Studio Pro applications.