An Uninterruptible Power Supply, also uninterruptible power source, UPS or battery/flywheel backup, is an electrical apparatus that provides emergency power to a load when the input power source, typically mains power, fails.
A UPS differs from an auxiliary or emergency power system or standby generator in that it will provide near-instantaneous protection from input power interruptions, by supplying energy stored in batteries or a flywheel.
The on-battery runtime of most uninterruptible power sources is relatively short (only a few minutes) but sufficient to start a standby power source or properly shut down the protected equipment.
A UPS is typically used to protect computers, data centers, telecommunication equipment or other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss.
UPS units range in size from units designed to protect a single computer without a video monitor (around 200 VA rating) to large units powering entire data centers or buildings.
Inverter
An inverter is an electrical device that converts DC (direct current) in to standard AC (Alternating current) that allows you to run electrical equipment. The inverter draws power from a 12 V battery or several batteries wired in parallel
There is a wide range of inverter like Videocon Inverter 800VA ECO TECH Series, Luminous 800va sine wave, Digital Inverter - 800VA etc available in market . Various size of inverters are available that depends on the watt (amps), you wants to run.