from vendors) are distinguished from visible watermarks (as in the photo to the left) and for which photographers have mixed feelings.
Copy protection? Many software programs, DVDs, and video games come with protection systems -- software that prevents the user from using it (not copying it) unless there is some verification of ownership. These systems alternately known as copy protection or copy prevention (also known as DRM or digital rights management) require users to work a little harder. A failure to supply the required code, serial number, or unlocking hardware prevents the program movie or video game from starting up. Many companies bypass such forms of DRM because they may get in the way of the operation of the device and because consumers disfavor them because of the extra layers required to activate. But DRM generally only works in the case of media that runs -- not passive media like photographs and documents. Moreover, few forms of DRM have proven uncrackable.