What does it mean when a hike is "unsupported"?
In an unsupported hike, I carry from the start all the gear, supplies, and food that I need to finish. (View my gear list to see all the contents of my pack.) I take water from creeks and springs along my route. This style of hiking may also be referred to as "alpine style" or "without resupply."
How does it compare to other styles of long-distance hiking?
Most hikers are "minimally supported" by existing infrastructure along the trail. To resupply they may buy provisions at the grocery store or receive a maildrop at the post office. They hitchhike into town, accept trail magic, eat at restaurants, and stay in motels. This style may also be referred to as "traditional."
It is less common to be "self-supported," or when supplies are cached beforehand along a route in order to improve comfort (through a lighter load), make particularly remote and/or water-less stretches logistically feasible, and eliminate the need to make time-costing trips into town.
Lastly, some people are "fully supported" by a dedicated cadre of handlers who wait at road crossings and trailheads in order to restock the VIP with enough food, water, and supplies to reach the next reunion point. Support crews also set up camp, prepare meals, give massages, and make supply runs, among other tasks.
Is it necessary to do the Long Trail unsupported?
No, absolutely not. There are many on- and near-trail opportunities to either purchase groceries or to receive a maildrop.
Then why are you doing it unsupported?
It is primarily about the challenge. To be successful I must plan and execute perfectly: the gear I start with must be appropriate for the conditions I will face; my supply and food stores must be sufficient to complete the objective; and my daily mileages must keep pace with my projections. Once I start, I cannot rely on civilization to bail me out. Success in this hike is not assured: a lot can happen over 15 days and 552 miles, especially given the time of year (late Fall) and some of the terrain (the Northeast is home to many of the most difficult miles I have ever "hiked").
The allure of an unsupported Long Trail Yo-Yo also has to do with its simplicity. The trip goes like this: start, hike, finish. I need not be concerned about post office hours, grocery store selection, motel vacancies, or hitchhikes. By going unsupported I minimize the interruptions to my outdoor experience -- for the entire length of my trip, it's just me, my surroundings, and my objective.