Based on the Rules of Thumb books published in the 80's by Huffington Press, RulesofThumb.org wisely moves the collection of tried-and-true common guidelines to the internet where online communities can contribute and the database itself can grow and remain organized. Rules of thumb, not always factual, are little rules passed on from generation to generation to make it easy to remember answers to complicated problems. Here's one on avoiding poisonous snakes - Red next to yellow can kill a fellow, but red next to black is a friend of Jack.