The UPS and the diesel generator are two devices for keeping a web server operational if there are troubles with the main source - an interruption or unreliable current that cannot keep the server working correctly, for example. UPS is an abbreviation for Uninterruptible Power Supply, even though it is sometimes referred to as Uninterruptible Power Source also. The UPS is, in simple terms, a highly effective battery which is connected to the web server and to the electricity network at all times, so in case there is any disruption, it's already functioning, that permits the hosting server to keep on doing the job without losing any data. The diesel generator is an engine that can power up the entire data center. It needs some time to start working and it's the UPS that provides this time. Those two power solutions are absolutely essential for any facility or provider that wants to prevent data loss and hardware damage caused by an unexpected electrical power issue.