Let me get right to the point: You need a UPS (Uninterruptable Power Supply, aka. “battery backup”) on most electronic devices you own, especially your computer. If you value your investment, or the data you have collected, don’t skimp here.
Without a UPS, your computer or other electronic device plugs into your electrical outlet and is subject to whatever voltage comes down the line. Low voltage (brownout), high voltage (spike or surge), or other conditions feed right into your device. This can cause minor damage or complete failure.
A UPS plugs into the outlet first. It conditions and protects the power it supplies to your computer. And they work well. If they don’t, most manufactures offer a warranty of coverage of ($25,000 or more) to compensate.
A UPS is commonly known to provide battery time to sustain your computer while the power is out. On a basic UPS you have 5-20 minutes, tops. This is enough time to save your work and shutdown. Or to prevent shutdown if your power is on the blinks. To provide sustained uptime, that would be a generator. 😉
Don’t wait for a problem to occur to take this serious. The common manufacture for UPSes is APC. Office Max sells these for $40 – $100.
Here’s a pretty well written FAQ I found online: http://www.jetcafe.org/~npc/doc/ups-faq.html.