Web hosting uptime is a measurement of the time a computer server has been running, the longer the web hosting uptime the better the service (usually). Uptime is important to not only web hosting companies, but to any person or company that has a website, because if a website is down it could hurt a personal company's reputation as well as the reputation of the web hosting uptime guarantee. Web hosting companies strive for a 99.9% uptime, which means that there would be less then 2 minutes of downtime a day.

Factors that impact a web hosting uptime are sometime unavoidable, but many companies strive to prevent downtime. Downtime can be classified in three ways: planned downtime which is caused when a server is updated or upgraded, semi-planned downtime which is caused when software companies find a security breach and a patch must be put into place, and the worst is unplanned downtime which can be caused by an overloaded server, a software/hardware malfunction, or malicious software.

Uptime guarantees made by web hosting companies are based off of past information. Web hosting uptime can be monitored and maintained a few ways. There are services that provide 24/7 monitoring. Large web hosting companies have their own departments that monitor their servers. A loss in web hosting uptime can be prevented by having a redundant server to fall back on incase the primary server goes down. For a planned single server change this method may be practical for a larger company, but the costs implied for an additional server in a smaller company or providing this for multiple servers in larger companies can be impractical. Unplanned downtime would also keep this method from working well.

Some niceties that many websites provide is a friendly downtime message that will still allow the user know that the site is only temporarily down. Larger web hosting companies are able to provide a quicker return to normalcy to maintain their uptime guarantee, because they have staff readily available to respond to a downtime error quickly. Smaller companies may experience a longer downtime.

For consumers, researching web hosting uptime can prevent a package from being purchased from a web host that has a lot of downtime. There are websites that track a company's web hosting uptime and provide reviews on the company freely for review. Other places to look for information are on forums either provided by the web hosting company or on web hosting review forums.

If your website does experience downtime you can contact the technical support or customer service department to see when your site will be restored. Understand that no web hosting company can have a 100% uptime guarantee. If your website experiences too much downtime switching to a different company with a higher and better web hosting uptime may be your only option.