UPS is an abbreviation for Uninterruptible Power Supply or Uninterruptible Power Source. That is a battery that is used to power a computer or a server in order to avoid the loss of data in case the main power source fails for reasons unknown or becomes risky. A diesel generator practically self-explanatory. UPSs and generators are used as a backup in data centers to back up the power supply and to ensure the consistent operation of all the servers located there. As the UPS runs all the time, it provides the necessary power for the web servers to remain functioning until the generator starts and takes over. Using such a backup is vital for any data center or service provider that wants to keep their hardware and data intact in case there is a power surge or outage, due to the fact that it offers them plenty of time to react until the issue is resolved and the primary power supply is restored.