Server uptime is a term used to describe the amount of time that a web server is fully functional and online. When a server crashes or goes offline, all of the web sites hosted on it are also rendered useless until it the problem is repaired. Thus, server uptime is direct indicator of the reliability and consistency of a web hosting provider.
Most web hosting providers have a seal posted on their web site that guarantees more than 99 percent uptime. While this may seem appealing, the truth is, most companies do not live up to this promise. If you have been experiencing frequent downtime then you may want to switch web hosting providers. Every time your site crashes you are potentially losing money. This is especially true if you are operating an eCommerce web site.