You've heard that new sport, geocaching, is fun. Or, you're tired of getting lost on your travels. Welcome to the 21st century. Global Postioning System (GPS) has been around long enough that prices are reasonable and the technology is user-friendly. With myriad brands and models, how to choose?

If you want a GPS for both hiking and driving use, then a handheld unit would be the way to go. Some handhelds even have accessories to allow them to be installed in an automobile. But don't rule out a PDA. More on that in a moment. For driving only, there are GPS receivers made just for vehicle use.

Handheld GPS receivers are either mapping or non--mapping. A basic, non--mapping unit can often cost less than $100 US and usually has/displays the following:

• Location
• Compass heading
• Elevation above sea level
• Accurate time
• Satellite location and signal strength
• The ability to calculate distance traveled
• The ability to record your path as a set of waypoints
• The ability to navigate routes
• The ability to retrace your steps

Handheld mapping receivers do all the above plus have the ability to display maps. The maps are either pre--loaded or uploaded from your PC. Prices are reasonable for mapping units, starting at around $150 US.

Paper maps are strongly recommended whether you're using a mapping receiver or not. Paper maps do not require batteries and probably won't go defective. Also, a paper map gives you a "big picture" view of your situation -- something lacking on the small screen of a GPS.

I mentioned earlier your considering a PDA with GPS capability. A PDA is bulkier and the battery life is usually shorter, but if you're using a PDA anyway, then there are several ways to turn a PDA into a GPS. Some PDAs accept a GPS "sleeve." That is a device that the PDA nestles into. Another choice is one of Garmin's PDAs. Garmin is probably the most popular GPS maker and they have one PDA/GPS that is Palm--based and one that is Pocket PC--based.

Prices for automotive GPS start at around $250 US. These provide turn--by--turn guidance. Spend a little more than that and you get voice guidance. These are larger than handhelds in order to accommodate a screen large enough to be seen while driving. They are powered by the car's electrical system and because of this, they can only be used in a vehicle.

Many automobile manufacturers now offer built-in GPS receivers as an option. Because they are built-in, the big advantages are security and aesthetics. They are quite a bit more expensive than add-on units and often have fewer options. I've also heard some stories of people having a hard time getting map updates.

A PDA/GPS is a good alternative for automotive use. Its screen is about the size of an automotive unit, so seeing the display is not a problem. They can also be powered by the car, eliminating battery worries. The Garmin PDAs mentioned above both come with the hardware and software for automotive use.

If you're hiking, a basic handheld unit (without maps) will be fine since you'll always have paper maps with you anyway (you will, won't you?). An advantage to a handheld mapping unit is that they usually have more advanced features than the basic units. For driving, you have the choice of a handheld, in--car dedicated, or PDA. The handheld does have limited usefulness in a car, as it does not provide turn--by--turn guidance. For a more detailed look at how to choose a GPS, click here.

J. Chartwell has developed Maps GPS Info.com, which provides practical information on GPS and maps that everyone can use. His website includes product reviews and a maps/GPS glossary.

• Easy Navigation in the Woods or on the Water with the Garmin eTrex GPS Handheld