Shelter
If you really hike the whole trail, you will have to sleep on the trail. You can carry a tent or a tarp and set it up wherever you find a good spot or you may choose to sleep in a shelter. There are shelters spaced out about every 8-12 miles on the trail and they are available on a first-come first-serve basis. Of course the mice get to stay regardless! Shelters are very good for protection when the weather is bad (rain, wind, snow) but typically you won't see as much wildlife if you stay at a shelter (because the animals stay away from the noise) so they can be good and bad. Also if you are hiking alone and feel lonely, you can always stay in a shelter at night to be able to talk with other hikers staying there.

Food
How much food you carry depends on how many miles you hike each day and how much you eat. Usually hikers will resupply their food every 100 miles or so and most often that depends on where the next town is on the trail. The average dry weight of your food supply should be 2 pounds/day so if you can hike 100 miles in five days you will need a minimum of 10 pounds of food but if it takes you seven days you will need at least 14 pounds. Once you are in the woods there are no 24-hour 7-elevens, so you MUST plan your food supply very carefully and you MUST ration your food EVERY DAY. You might think, well why not just bring extra food so you never run out? Well let me remind you that you have to CARRY it ON YOUR BACK over mountains all day long and believe me you don't want to feel the burden of one extra ounce in your pack. If you eat 4 pounds of food in one day because you were really hungry, then you will have NO FOOD left for your last day into the next town. This sounds easy enough but it's a CONSTANT struggle. For the first six weeks or so it's not too bad because you still have fat on your body and you're not in a constant hunger mode. But as your body turns into a hiking machine that pounds out 15-25 miles/day, you quickly find that you are ALWAYS hungry! They say you burn anywhere from 6000-8000 calories/day thru-hiking, and 2 pounds of food is just NEVER enough. So you are constantly tempted to eat your food and you are just never satisfied. That's when towns really become an oasis on the trail because you can EAT all you want AND you can have ice cream, vegetables, fruit, and beer - all the things that are too heavy or perishable and cannot keep in the woods. It is not uncommon for a thru-hiker to hike 30 miles into the night just to get to town for the Pizza Hut All-You-Can-Eat (AYCE) Lunch Buffet!

Water
Then there's water. You get your water from springs, streams, creeks, ponds, lakes, but preferably springs. The water should be treated if you don't want to risk getting a parasite or some type of bacteria. Most hikers use either iodine tablets, chlorine bleach, or a small water filter. Again, the rationing comes into play because if you haven't noticed, water is HEAVY! So unless you want to carry excess dead weight on your back, you have to figure out how much water you will need until the next water source and carry that much. (It's not something to "figure out" really, it's just a matter of getting to know your body and planning accordingly).

Guidebook
There is a wonderful book published by the ATC called the AT Data Book, and in that book you will find mostly all of the logistical information that you need to hike the AT. Mostly all of the water sources are listed by mile for the entire length of the trail. It also lists road crossings and tells you in which direction and how far there is a town. In addition, it tells you where the shelters and campsites are so you can plan your mileage for any given day. It works like this: You may cross a road in Virginia called Rte. 62, say. That road will be marked in the Data Book as mile 595 on the trail (from Springer Mountain, GA). At mile 597 there is a spring, and at 599.8 there is a shelter with a water source. So when you get to that road you know you can hike another 4.8 miles and get to a shelter. So you can pretty much always know where you are, at least in relation to the nearest road and town. Many people choose to carry maps as well, but I didn't want the extra weight so I just used the Data Book and it worked out fine.

Resupply / Towns
When you thru-hike the AT, you don't actually live in the woods for the ENTIRE time, although you certainly can if you so choose. Mostly all thru-hikers go into town about every 100 miles to resupply their food, take a shower, do laundry, call home, replace or repair gear, check email, oh yes, and EAT! The "trail towns" are very used to seeing smelly, dirty backpackers wandering through their streets. Many towns have hostels just for the hikers. In Palmertown, PA hikers are allowed to stay in the town jail for free. At the Ben & Jerry's in Manchester Center, VT thru-hikers get a free Peace Pop. In Kent, CT hikers get a free beer at the liquor store if they sign their map on the wall. Some stores will take a polaroid of you and add you to their wall of thru-hikers for that year.

The challenge of getting to town is not being there, but being able to break away! We call it the "town vortex". Especially if the weather is bad it can be very hard to leave the comforts of a bed, shower, dry clothes, and food and drag yourself back into the woods. It's just another of the many obstacles on the trail...