This is a potential security issue, you are being redirected to https://csrc.nist.gov
For the purposes of this Recommendation, a value in a set that has an equal probability of being selected from the total population of possibilities and, hence, is unpredictable. A random number is an instance of an unbiased random variable, that is, the output produced by a uniformly distributed random process.
NIST SP 800-90A Rev. 1 under Random Number