What uptime means in real terms

When you're looking for a Web host, you'll probably notice the big red numbers splashed all over their screens proclaiming 99% (or higher) uptime. Since most of them offer this level or better of uptime, it hard to use this criteria as a way of choosing your Web host. And while I definitely recommend getting a host that offers at least 99% uptime, you should be aware that 99% uptime equals about 1 business day down every month. The fact is that unless you have super redundancy, which is extremely expensive, you're going to have some website downtime periodically. In a test Watchmouse did from January 20 to February 24, 2010, only two of the NASDAQ 100 sites had 100% uptime: Google and RyanAir. And 73% of the top 100 sites had an uptime less than 99.9%. This doesn't mean that those 73 sites should change hosting providers, (well perhaps Qualcomm and Millicom should). It means that they will be reimbursed for the time that their sites were down.