An important aspect of using a topo map is the fact that you can pin-point a location on the earth, transpose that location onto the corresponding map with fair precision and then communicate that location to others. This allows you to locate and share items such as link-up points, caches, targets, en route rally points, etc. The most efficient method is the grid reference system.
I won’t go into a detailed topo map discussion here, Max Velocity’s already done that on his site with an excellent primer. He explains how to locate a point on any 1/25,000 OR 1/50,000 topo map using the Military Grid Reference System (GMRS). If you are attending his course he has written that this is the map system he will use. He goes on to write that you can buy any USGS topo map with the GMRS grids pre-printed on your personalized map at mytopo.com. I have ordered maps from them and I highly recommend them.
For those folks who already have a stock of USGS maps that are 1/24,000 maps, have the ability to print their own maps or have compasses in 1/24,000, I will explain how simple it is to draw a grid system on your map. The following is taken directly from maptools.com:
