Computers can't generate completely and totally random numbers and most algorithms make use of a pseudorandom number generator. A pseudo-random number, also known as a pseudo-random variate is a random choice made by an algorithm that follows rigorous mathematical rules.
Statistical estimates show that such algorithms would produce the same sequence (specific distribution) for each run of the computer program; in many practical applications, this does not matter at all; but when performance is critical, e.g., in cryptography or gambling, this repetition may lead to an exploitable pattern or "tell," so it's important to ensure pseudorandomness with good security and encryption techniques...