We've talked a lot about the idea of ormartinal cost. For example, it'sn electra tacry rate. I can send out one email and it's basically the same price for me to send it to ten people as to send to a hundred people or a thousand people. On a marginal basis, it cost zero for facebook to provide a unique page to every single person on earth. It's zero's all the way down. And so this idea of margional cost, this is the key to understanding soutwere and technology, period.