Random numbers are the numbers produced by a truly random mechanism (in contrast to pseudo-random numbers). For example, random numbers with a good degree of randomness may be produced by tossing a coin, recording “0” or “1” (instead of “head” or “tail”), and converting the sequence of “0” and “1” as a sequence of digits in the binary notation of a number into a decimal number.
Random numbers may be obtained in limited quantities in computers, e.g. using the least significant digits of the moments of some events, like pressing a key or moving the mouse. In professional unix-like operating systems (OS), for example in Linux, this capability is implemented right into the OS itself.