For those of you who may not be familiar with some of the backpacking/hiking terms and slang, here’s a little help:

AT: short for “Appalachian Trail”.
Shelters (also called huts & lean-tos): A three or four sided wooden or stone building, spaced out usually between 5-15 miles apart. Most are near a water source, and some have a privy.
Hiker Midnight: when the sun goes down, regardless of time of day, unofficial “quiet hours” should be observed.
Springer Mountain: in North Georgia; summit is the southern terminus of the AT
Katahdin (Baxter Peak): in Maine; the northern terminus of the AT
NOBO: Northbound (in a direction from Springer towards Katahdin). Trail north isn’t always compass north.
SOBO: Southbound
White Blazes: 2″ x 6″ vertical white rectangles that are placed at eye height on trees and other objects, in both directions, to mark the official route of the Trail.
Blue blaze: Spur trails off the AT to views, shelters, water sources etc.
Double blaze: Two blazes, one above the other as an indication of an imminent turn or intersection in the trail.
Hostel: An establishment along the trail (or nearby) that has bunks, showers, and sometimes cooking and maildrops, for AT hikers. Some are nicer than others.
Register: A log book normally found at a trail shelter or a trail head or upon entering officially designated Wilderness areas. The original intent was for hikers to sign in so a searcher needing to find a lost hiker could tell where they last were. Some hikers often post hilarious entries or illustrations in the shelter books.
Section hiker: is a person who is attempting to complete the entire Appalachian Trail by doing a series of section hikes over a period of time.
Slackpacking: getting someone to carry your main pack any distance along the trail for you, enabling you to carry a smaller backpack and hike faster.
Stealth camping: a manner of camping where there is no indication that you are there, and no trace of your being there is left when you’ve left. There are countless “established” (but unofficial) sites all along the trail.
Stile: Steps or passageway constructed over or through a fence to allow people, but not livestock, to pass.
Switch Back: A turn that takes the hiker 180 degrees in the oposite direction.
Trail Magic: Any unexpected food , water, or other beverages provided by other people on the trail. This can range from a small cooler by a trailhead to a full blown cookout (“Hiker feed”). Trail Magic is always welcomed. ALWAYS.
Yogi: “letting” food be offered cheerfully by strangers without actually asking them directly. Think Yogi Bear.

When I use a mile marker (i.e mi 483.2) that’s the mileage NOBO from the AT’s southern terminus on Springer Mountain, as per the ALDHA’s (Appalachian Long Distance Hiking Association) AT Thru-Hiker’s Companion.

Finally, there may will be times when I slip up and use 24 hour military time. It just comes naturally for me, and writing “a.m.” and “p.m.” all the time is a PITA.

Other hiking slang and terms can be found here.