A Cairn is a human-made pile or rocks that have been used to mark trails across a landscape since prehistoric times. They are placed at regular intervals along a trail. A series of cairns can be used to show a path across difficult terrain and often placed at junctions or in places where the trail direction is not obvious. Basecampers earn Cairn badges to demonstrate their achievement in a skill along their trail to the Everest Summit award. Some examples of Cairn badges are: Navigation, Backpacking, Cooking, Astronomy, and Fire Craft.