What is the purpose of a UPS battery backup?

A UPS is an abbreviation for an "Uninterruptible Power Supply". The purpose of this device is to provide power when the main power source fails. UPS battery backups are used to provide power for computers, data centers and various other types of equipment. Typically the back-up is used with equipment that cannot have a disruption in the power supply, or equipment which may be damaged if there is a disruption in the power supply.