Although mainstream music has embraced the Liquid Audio format because it prevents illegal copies, the site still has a limited inventory, with only 50,000 titles.

The software is a form of release-date checker, designed to prevent copies of the game from being played before the release date in that territory.

Patents were once used to prevent obvious copies of the products from which companies expected to earn profits.

Unless there is some way to prevent copies from competing at the marginal cost of production, companies don't invest in making the invention a product.

Until a few years ago microsoft prevented unauthorized copies of windows to install updates.

StarForce copy protection is used to prevent illegal copies of the game from being produced.

Note that the intent is to prevent all copying, both pirate copies and legal copies of one's own content, for example, for format shifting.

Medeco uses patented key control systems, including patents on the keys and the cylinder, to prevent unauthorized copies of keys from being generated.

At the same time, the producers of these devices are expanding the use of digital rights management systems in order to prevent unauthorised copies.

The point of this is to prevent simple bit-by-bit copies, since the Volume ID is required (though not sufficient) for decoding content.