Ha, my daughter asked the same question, so I tried explaining all 4 rules, but she didn't seem to be very impressed. So I quickly googled, found this http://www.bitstorm.org/gameoflife/ among the top result, and we went through all 4 rules, experimenting. That was a lot more interesting, especially when she found out about the 'objects'... :) So the page is bookmarked now :)