Uninterruptible Power Supplies (UPS) regulate any irregularities that may be intermittently present within your electricity. However, most UPS units DO NOT condition the power, nor isolate your system from ground spike disturbances that happen all day long.  This is where power conditioners are needed.  The biggest advantage of a UPS is that if there is a power failure, the battery back up takes over in a fraction of a second and supplies the power to the computer without the computer ever knowing a power failure existed.  This safely gives the computer user time to systematically shut down the computer without any "surprises" happening to the system. Most UPS units provide software to use along with a USB connection cable to the server.  This software will control the server, and will initiate a system shutdown if the UPS is running on battery power for an extended period of time.  After power is restored, the server is automatically powered back up.  This helps provide a systematic shutdown as opposed to an abrupt power-loss.