CD key

A string of numbers or characters that often come with computer games or software. The user is required to input the CD key to install the product or play online. A CD-key is verified by being plugged into a mathematical formula and checking to see if it returns the proper value. For example, a very simple CD-key system would check to make sure that all the numbers in the CD-key add up to a specified number. In addition to this, many games and software products require you to verify your CD-key over the internet. However, this doesn't stop people from creating "keygens" or programs that automatically generated valid CD-keys.