We just created a program to generate pseudorandom numbers, but every time we run it we get the same results. We know that these numbers are the results of complex equations and algorithms, so why are they the same? It's because each time we run the program, we're starting with the same seed.
A seed provides a starting point for an algorithm. So, in the previous example, yes we're using complex algorithms to generate numbers, but we're kicking off the algorithm at the same point each time. No matter how complex the algorithm is, if you start at the same point, and perform the same operations, you're going to get the same results.
Imagine that we have three people, and each person is about to walk the same path by 5 steps. If ...