Fording is crossing a river or stream on foot where there is no bridge. Hikers face upstream or angle across, unclip the pack hip belt, use trekking poles for stability, and judge depth and current carefully. Swift water is deceptively powerful, making fords one of backpacking's real hazards.
The Yosemite class rating system describes how difficult and exposed terrain is to travel, from Class 1 to Class 5. Class 1 is walking, Class 2-3 is steeper hiking and easy scrambling, Class 4 is exposed scrambling where many use a rope, and Class 5 is technical roped climbing. It helps hikers gauge a route's seriousness.
The alpine zone is the ecological region above treeline, where harsh cold, wind, and short summers allow only low-growing, fragile plants like grasses, sedges, and cushion plants. It offers stunning open terrain but is highly sensitive — hikers stay on rock or trail to avoid trampling vegetation that takes decades to recover.
Treeline (or timberline) is the elevation above which trees can no longer grow, due to cold, wind, and a short growing season. Above treeline the landscape becomes open alpine terrain — more exposed to weather, harder to navigate, and ecologically fragile — so hikers take extra care there.
A ridge is a long, narrow elevated crest of land where two slopes meet, running between or up to summits. Ridge hiking offers expansive views and a natural line of travel, but exposed ridges catch wind and weather and can involve scrambling, making them exhilarating but sometimes serious terrain.
A saddle is a low point on a ridge between two higher summits, shaped like a horse's saddle. Also called a col or pass, saddles are natural places for trails to cross a ridge and often mark the low point between two peaks on a traverse. Their shape can also funnel and accelerate wind.
A false summit is a high point on a mountain that looks like the top when viewed from below but turns out to have more climbing beyond it. False summits are notorious for sapping morale and energy on long ascents, as hikers crest them expecting the top only to see the true summit still ahead.
A lollipop loop is a hike shaped like a lollipop — a single stretch of trail (the 'stick') leading to a loop (the 'candy') and back out the same stick. It combines a loop's varied scenery with an out-and-back's simple start and finish, and is a very common trail layout.
A loop trail is a hike that returns to its starting point by a different route, forming a circuit so you never retrace your steps. Loops offer constantly changing scenery and a satisfying sense of a complete journey, though they can be harder to navigate and to bail out of than an out-and-back.
An out-and-back is a hike that follows the same trail to a destination and then returns by the identical route, retracing your steps. It's the simplest hike type — easy to navigate and to turn around on — though you see the same scenery twice, unlike a loop.