List of random number generators
Random number generators are important in many kinds of technical applications, including physics, engineering or mathematical computer studies (e.g., Monte Carlo simulations), cryptography and gambling (on game servers). This list includes many common types, regardless of quality. Pseudorandom number generators (PRNGs). Whenever using a pseudorandom number generator, keep in mind John von Neumann's dictum "Anyone who considers arithmetical methods of producing random digits is, of course, in a state of sin." The following algorithms are pseudorandom number generators. Cryptographic algorithms. Cipher algorithms and cryptographic hashes can be used as very high-quality pseudorandom number  generators. However, generally they are considerably slower (typically by a factor 2-10) than fast, non-cryptographic random number generators. These include: A few cryptographically secure pseudorandom number generators do not rely on cipher algorithms but try to link mathematically the difficulty of distinguishing their output from a `true' random stream to a computationally difficult problem. These approaches are theoretically important but are too slow to be practical in most applications. They include: Random number generators that use external entropy. These approaches combine a pseudo-random number generator (often in the form of a block or stream cipher) with  an external source of randomness (e.g., mouse movements, delay between keyboard presses etc.). Random number servers. The following (non-exhaustive) list of websites claim to provide random numbers generated from a truly random source, with many providing additional randomisation services: