Why should I bring it? WHAT DO YA' MEAN! So You Don't Get Lost. Or if you do, so you can get found.

What kind should I get? Just any old compass as long as it points north 99% of the time will work. Why 99% and not 100? Because a compass that points north 100% of the time is impossible to get. There are times when you take a bearing right next to a large, magnetic boulder. To make sure I don't do this, I move around and see if the needle changes direction. It really helps you to determine the altitude Gain/Loss if you use a USGS Topographical map (available at most outdoor stores or you can create one using the USGS TOPO!™ software). And you should take a class on how to use them. Many towns offer these classes as well as an orienteering club.