An uninterruptible power supply or uninterruptible power source (UPS) is an electrical apparatus that provides emergency power to a load when the input power source or 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, supercapacitors, or flywheels. The on-battery run-time of most uninterruptible power sources is relatively short (only a few minutes) but enough to start a standby power source or properly shut down the protected equipment. It is a type of continual power system. As the world becomes more reliant on secure data, UPS systems, which supply emergency power to a system if the grid goes down, are becoming an essential part of our lives. These UPS are categorized into two types: Online UPS and Offline UPS.