Linear-feedback shift register

A linear-feedback shift register (LFSR) is a way to make a pattern of numbers that looks random. It's like a machine that you put a number into, and then it spits out a new number each time. It does this by taking some of the numbers it already has and combining or changing them to make a new one. This machine can make a very long pattern of numbers that looks random but stays the same if you put the same number into it.