UPS is an abbreviation for Uninterruptible Power Supply or Uninterruptible Power Source. This is a battery that is used to power a PC or a web server to prevent the loss of data in case the main source of energy fails for some reason or becomes unsafe. A diesel generator pretty much self-explanatory. UPSs and generators are used as a backup in data centers to back up the main power source and to guarantee the continuous operation of all the machines located there. Because the UPS works constantly, it provides the necessary power for the web servers to remain functioning until the generator starts and takes over. Using such a backup is a must for any data center or provider that wants to keep their hardware and data intact in the case of a power surge or outage, because it provides them with enough time to react until the issue is resolved and the main power supply is restored.