The A.T. is marked for daylight travel in both directions using a system of white "blazes," or a rectangle of white paint 2 inches wide and 6 inches high. Blazes are found most often on trees, occasionally on posts and rocks.
Piled rocks called "cairns" are also used to identify the route above treeline. Side trails and shelter trails use blue blazes. Distance between blazes varies, but if you have gone a few hundred yards without seeing a blaze, stop. Retrace your steps until you locate a blaze. Then, check to make sure you haven't missed a turn. When your map or guidebook indicates one route, and the blazes show another, follow the blazes.
In the 25 federally designated wilderness areas the A.T. passes through, blazing is intentionally much less frequent and signage is minimal to retain the wilderness character of the land. Blazes may be 1/4 mile apart. Side trails may not be marked. Carrying a map and compass are especially important in these areas, found in Georgia through Virginia, and Vermont and New Hampshire.