/dev/random and /dev/urandom

This is likely common knowledge, but I hadn't possessed it before. I'd always wondered why sometimes something like

cat /dev/random > randomStuff

would be so oddly-behaved.

It's because /dev/random will block until there is sufficient data floating around in the system (keystrokes, network packets) for the OS to come up with something sufficiently random. /dev/urandom just degrades your random-ness in order to stay speedy. Cool.