UPS is an abbreviation for Uninterruptible Power Supply or Uninterruptible Power Source. This is a battery used to power some type of computer or a web server to avoid the loss of data in case the main power source fails for some reason or becomes risky. A diesel generator practically self-explanatory. UPSs and generators are widely-used as a backup in data centers to back up the power and to ensure the constant functioning of all of the servers located there. Since the UPS works at all times, it provides the required power for the machines to remain functioning until the generator starts and takes over. Using such a backup is critical for any data center or web hosting provider that wants to keep their hardware and info intact in case of a power surge or outage, due to the fact that it gives them lots of time to react until the problem is resolved and the main power supply is restored.