An illegal prime is a special prime number. Such prime numbers are called illegal, because there is a way to change them, so that they yield something illegal: a program to circumvent the Digital Millennium Copyright Act. One of the first people to find such a prime was Phil Camody. In 2001, he found a prime that contains the gzip compressed source code for a program that can circumvent the Content Scrambling System. The Content Scrambling System is used as a way to prevent DVDs from being copied. Later, other primes were found that resulted in directly runnable programs.