The UPS and the diesel generator are two means for keeping a web server working if there are troubles with the main power supply - an interruption or unstable current which cannot keep the server functioning properly, for example. UPS is an abbreviation for Uninterruptible Power Supply, though it is oftentimes called Uninterruptible Power Source too. The UPS is, essentially, a highly effective battery which is connected to the server and to the electric power network all of the time, so in case there is any disturbance, it is already operating, which allows the server to keep on running without losing any information. The diesel generator is an engine that can power up the whole data center. It does take some time to begin working and it is the UPS that provides that time. These two power solutions are fundamental for any facility or service provider that wants to stop info loss and hardware damage resulting from an unexpected electrical power problem.