Uptime is the percentage of working time of website that refers to amount of time the server is running. For example, if some host has an uptime average of 99.86% that means your site will be down for almost one hour each month. This is most important aspect of website that it should be available to your online visitors all times. Keep it in mind that there is no 100% guaranteed uptime and no web hosting company or server can claim to have such performance. Uptime is like air because there is no surety about its presence. Lots of webmasters take uptime for granted. Uptime is amount of time that represents running of web server without interruption. This continuous running of the server keeps your website visible on the web to anybody who wants to look at it.
Lots of web hosting companies claim that they can achieve 99% continuous uptime. If you ever noticed a company claiming that it can achieve 100% uptime then avoids it because it can be fraud. They are basically claiming about 100% perfection that is something unbelievable because no organization can achieve this level.
Downtime is also a part of web hosting and all web hosting companies schedule downtime on frequent basis to maintain their servers and to install security patches. This downtime is normal part of web maintenance and customers are usually told in advance about this maintenance. Downtime only creates problem when it happened unexpectedly. There are lots of reasons for this to happen from power failure to technical malfunction. An efficient web hosting company will put contingency plans to deal with these types of events. They have emergency generators to restore power and clustered servers that can take over if a single server fails.
Webmasters should have knowledge about all web hosting emergencies. They must possess ability to deal with these types of situations because success of whole business depends on your efficiency. Uptime keeps your website running and if you want to make your website successful then it should be available to everyone in the world for twenty four hours a day. If it is unavailable for visitors then they will definitely go to other website and you will lose money. If you think on global scale of internet then even for a downtime of one minute you can lose thousands of dollars. Downtime is dangerous for large as well as small businesses.
If you are running a personal website then you may not lose money as a result of server downtime but you can lose your credibility. Certainly, web hosting companies are aware of importance of server uptime because profitability of their business depends on it therefore they try their level best to avoid this situation. They know that if their services crash for long time then they can desert their customers. It is also dangerous for their reputation because no one will trust them. By considering all these problems, web hosting companies offer a service level agreement (SLA) to their customers for setting out the amount of uptime that they will deliver and the recovery time should the unexpected occur. This SLA can outline a compensation scheme should the company fail to meet those standards. As a webmaster you are justifiably concerned about uptime and you should look for SLA before signing up to a web host.