The UPS and the diesel generator are two means for keeping a web server functional in case there are troubles with the main source - a disruption or unreliable current which cannot keep the machine functional, for example. UPS is an abbreviation for Uninterruptible Power Supply, although it can often be referred to as Uninterruptible Power Source too. The UPS is, basically, an effective battery which is connected to the web server and to the power network all of the time, so in the case of any disturbance, it's already functioning, which enables the hosting server to keep on doing the job without losing any data. The diesel generator is an engine that can power up the whole data center. It does take some time to start working and it is the UPS that provides this time. Those 2 power solutions are fundamental for any facility or provider that wants to stop data loss and hardware damage resulting from an unexpected power problem.