Random number generators are important in many areas, including physics, engineering, computer studies (such as Monte Carlo simulations), cryptography, and gambling on computer servers. This list includes many common types, even if they are not the best for certain tasks.

Pseudorandom number generators (PRNGs)

The following algorithms are pseudorandom number generators. They are simple to use, work quickly, and are not commonly recognized. When set up correctly, they pass all current tests that evaluate randomness. They are mathematically proven to eventually reach a stable state. They can be adjusted to function for any desired length of time and perform better in complex calculations and with greater accuracy.

Cryptographic algorithms

Cipher methods and secure data checks can be used to create very good fake random number makers. However, these methods are usually much slower. They are about 2 to 10 times slower than other fast, non-secure random number makers.

Some secure fake random number makers do not use cipher methods. Instead, they connect the challenge of telling their output apart from real random numbers to hard math problems. These methods are important in theory but are too slow to be useful in most real-world situations. They include:

Random number generators that use external entropy

These methods use a pseudo-random number generator (which can be a block or stream cipher) along with an outside source of randomness, such as moving a mouse or the time between pressing keyboard keys.