There are “shelters” along the Appalachian Trail, set aside for any hiker to stay for free. These are usually three-sided structures, open on the fourth side. 
Older shelters (from the 1930s onward) are quite simple with no light other than what comes in under the overhang on the front opening. (Notice that even in daylight one needs a headlamp to read.) 
Newer shelters are often more elaborate, with decks, picnic pavilions, lofts, skylights, and more. Like the trail itself, all are maintained by volunteers. 
Shelters range in size, offering space for 4-10 hikers to sleep. Air mattresses and sleeping bags are spread on the platform (always at least one step above the ground, sometimes at seat height, sometimes with bunk platforms). Backpacks, coats and wet gear hang from pegs. Walking sticks and boots are usually jumbled in the corners. 
Shelters have nearby tent sites, some type of privy, a picnic table and a fire ring. Newer shelters have a picnic pavilion which can double as extra sleeping space on stormy nights when the shelter itself is full! 
Shelters are spaced 5-13 miles apart. Whenever possible, we enjoy staying at a shelter because of the extra conveniences and because of the social interactions with other hikers. Since we hike short daily distances, however, we sometimes have to find a flat area to pitch our tent for a night between shelters. That has its own charms, including a sense of accomplishment that we can, indeed, be self-reliant. 
No matter where we end up for the night, we always sleep well. A day of hard exercise certainly helps!
October 15, 2015 at 1:27 am
It is fun following your trail experience. Take care.