Atomic watches, more accurately called radio controlled watches, are the most accurate wrist watches in the world. It is estimated that an atomic watch will lose less than one second, over the course of three million years.

By receiving a radio signal that contains the time and date code from one of the atomic clocks that keep the world's time, an atomic watch automatically calibrates itself to the exact time. They self-adjust for Daylight Saving Time, leap years, and even leap seconds.

These watches contain radio receivers that are tuned to a specific frequency. The frequency varies, depending on where you live. If you live in the U.S., for instance, the radio station carrying the time code frequency is WWVB. This is a radio transmitter dedicated to the time code from the atomic clock at Fort Collins, Colorado.

When you purchase an atomic watch, the only thing you need to do, is set your time zone. This simple process usually entails scrolling through a menu, to select the area in which you live. Once you have done that, the watch will automatically update several times a day. This usually happens late at night, because there is much less radio interference at this time. It may also be necessary to leave your watch near a window, to maximize reception. A time, day and date update usually takes about five to seven minutes. It is important that you not move the watch, or push any buttons while it is receiving.

As long as you are within a 2000 mile radius of the transmitter to which your watch is tuned, you should receive regular updates. This covers just about all of the U.S., with the exception of Alaska and Hawaii.

If you travel outside of this radius, your atomic watch will continue to function as (and with accuracy comparable to) a quartz watch. Once you are back within range, it will update at the normal times.

There are a few other factors that may effect your watch's ability to receive the signal. You may have difficulty if you are in a vehicle, in or around tall buildings, or in a mountainous area. Most manufacturers have accounted for this, by adding a "manual receive" feature. With this feature, you can manually activate the receiver when you in a more suitable area.

OK, so you probably don't absolutely need one. But if you're shopping for someone who loves watches (and there are a lot of us who do), this should top your list. A watch fancier may take a certain level of pride in knowing that there is no watch more accurate than theirs.

They are available in digital, chronograph, or a combination of both. There are sport models, casual, and business models. Most are water resistant, to one degree or another (mine is resistant to 100 meters). They can be found for prices starting at around thirty dollars, and ranging well into the hundreds, depending on the style and features you want. Regardless of how little, or how much you spend, they all maintain the same unparalleled level of accuracy.

There are a number of companies that make atomic watches, but Casio seems to dominate the U.S. market. Their Wave Ceptor line of atomic watches runs the gamut, in terms of styles; and range in price from around forty dollars, to over three hundred. I tend to shop from the lower end of the price range, but both of my Wave Ceptors have absorbed a lot of abuse, with no sign of distress.

You could spend thousands of dollars on a Rolex (if my wife is reading this, I am partial to the Submariner), but even that time honored name, cannot keep better time than my forty dollar atomic watch. These little gadgets are clearly the way to go, when you want to know what time it really is.