Definition: random number generator
A software routine that produces a random number. Used in applications such as computer games and cryptographic key generation, random numbers are easily created in a computer due to many random events that take place. For example, only the difference of a few milliseconds between keystrokes is enough to seed a random number generation routine with a different starting number each time.
Once seeded, an algorithm computes different numbers throughout the session. The numbers that are created must be distributed evenly over a certain range, and they cannot be predictable (the next number cannot be determined from the last).