It's "difficult" for computers to make truly random numbers. The
seed initializes the pseudo-random number generator. Without a seed, or if you use the same seed every time, you'll get the same sequence of "random" numbers every time. In some applications, that's "random enough" but generally if you're looking for something random you want different results every time.
I don't know where the random seed comes from, but frequently it comes from the clock. i.e. You are unlikely to click the "seed" button at exactly the same time every day, down to the millisecond (or microsecond), so every time you click it, you get a different seed and a different "random" sequence.
Midi Humanize Via Random Seed
Linear Mode
