I'm currently pre-planning a trip to A.T. I've worked out my flight and from searching Google, I've found some keen points of interest. Although I'm unfamiliar with "shelters" and re-applying at locations. Could anyone expand on this?

The shelters are generally open faced small buildings that are used for sleeping in. They are usually 5-10 miles apart so hikers can sleep in them overnight without having to set up tents. Depending on the time of the year, you may end up sharing them with other hikers. Note that mice often can be found in them.

There set up along some points on the trail. You can set up camp for a night. Good for those rainy nights.