A what? UPS? Isn't that the name of a shipping company? Well, that too, but it's also an invaluable and oft-overlooked piece of electronic hardware. The acronym similarity is simply a coincidence. A UPS is a battery-backup, it's a surge-protector, it's insurance, and it's generally a good idea.
Here's what's happening in your house right now: The electricity you get from your local utility company comes through the plugs on your wall at approximately 115 volts. I say "approximately" because the voltage on which your electronics feed varies a bit based on the activity of other devices in your house. For instance, if you're using your computer and the washing machine goes on, the voltage may dip down a few volts. You might notice that the lights dim slightly, and then return to normal. Basically, you're experiencing a small brownout and, for the most part, robust electronic devices such as lights and appliances don't really care. The more complex the electronics within the device, the more sensitive it is to fluctuations in its supply of electricity. Your computer is the most complex electronic device in your house. And it should be, it cost you enough. Many hardware and software issues can be attributed to just a bad power feed, and could have been avoided by spending $50 to $100 on a UPS. Other consumer electronics devices, such as stereo equipment, can also benefit.
How is a UPS going to help? A UPS looks like (and weighs as much as) a really big brick. It has one power cord coming out of it which plugs into the power socket on your wall, and it has several sockets on its back for plugging in your various devices. Inside the brick is a big battery. The power comes in, is stored in the battery, and then delivered to your devices in a perfect sine-wave of 115 volt power. This makes your computer very happy.
In addition a UPS has a few added benefits: If the power goes out while you're typing your masterpiece novel (and you haven't hit Save all day), your computer will continue to run for a few minutes. Generally, it's just enough time to hit save and shut down your computer properly before the battery runs out. More common that a complete power failure, however, is a short brownout. When this happens, the power goes down for less than a second and then comes right back on. Computers hate that more than anything. Your UPS will completely protect your equipment during such an event. Also, the UPS will protect your equipment against even the most powerful power surges.
Convinced yet? Good. Here's what to look for:
The amount of power that a UPS can supply is measured in "VA" aka volt-amps. The higher the VA rating, the more equipment you can stick on a single UPS and/or the longer that equipment can run once the power goes out. If you have desktop computer, LCD monitor, and maybe a few small incidental peripherals, you should look for at least 500VA. If you have a CRT monitor (a tube), then you probably need more like 800VA. With that configuration, you may not get more than a couple minutes in the event of a power failure, though it will work great against brownouts and slight power fluctuations. If you want more battery-time, you may want 1000VA. If you have two large computers, or perhaps some serious stereo equipment in the same room as your computer, maybe 1500VA is more up your alley.
Also, look for a UPS that will connect to your computer via USB. That way, if you're not in front of your computer when the power goes out, the UPS will actually tell your computer that it's about to run out of power and automatically shut down your computer for you. Pretty slick.
Now that you're going to get one, there are some things you should know:
First of all, NEVER plug any device into the UPS if it draws a lot of power, such as: Power tools, vacuum cleaners, kitchen appliances, laser printers (ink jets are fine), heaters, fans, sewing machines, clothes irons, or other small appliances. For the most part, those devices are not on very long, they're robust enough to withstand power fluctuations, and if the power goes out, you don't lose anything.
You should also know that, eventually, you'll have to replace the battery inside your UPS. Generally it will last about 5 years, after which you can purchase a replacement battery, and please, please, PLEASE RECYCLE THE OLD BATTERY. Very often the company from which you purchased the replacement will recycle the old one for you.
Take care of your equipment, and it'll last to serve you another day.