Trail guide

Trail guides come in two main forms:

Trail guides available at the [[trailhead], park visitor center, etc. These normally include a map of one, specific trail, possibly linked with interpretive signs along the trail giving information on geology, history, or biology along the trail. These guides are often free, or available for a very inexpensive (ie: 25 or 50 cents) donation, paid on the honor system at the trailhead. The donation usually goes either to trail maintenance or to support a friends of group. If you're doing much hiking within a single park, you will likely collect quite a few of these before you're done. Since there's no change available, it's acceptable to pay a dollar, or five dollars, then take trail guides at each trail until you're caught up with the cost of the trail guides, just so you're in the same park. If you don't want to keep the trail guide, if it's in good condition, feel free to drop it back onto the stack for the next person.

Trail guides in book form. Most national parks, and most other major hiking areas with lots of trails, have trail guides available. These books, generally selling for under $20, usually provide basic maps with trail descriptions, a summary of park rules, and any special hazards (ie: bear information, etc.). If you're planning a trip to a distant park, this can be useful to pick up, although these are slowly being replaced by web sites like Trail-Finder.com.