switchback — an established hiking trail that zigzags across steep terrain.
trailhead — the starting point of a trail, usually marked with a sign.
tread — the pattern on the outer soles of hiking boots or trail running shoes.
trek — a multi-day hike in remote and exotic locations, often requiring the assistance of a guide.
understory — refers to vegetation (ferns, shrubs, saplings) growing beneath the forest canopy.
USGS — U.S. Geological Service, the federal agency tasked with monitoring and accessing the overall health of America’s ecosystems. Publishes highly detailed topographical maps frequently carried by hikers in the backcountry.