Beacon

Beacons are columns of light in SS undefined and Zelda Wii U.

Skyward Sword
In SS undefined, when Link places a Beacon on his map, either on The Surface and The Sky, a blue column of light will appear, acting as a waypoint to reach the desired location. Beacons can only be placed on overworld maps by pressing the C Button.

The power to place beacons is only activated after Link first talks to the aged Impa in the Sealed Temple, at which point only one beacon can be placed at a time. Once Link reaches the northern portion of the Lanayru Desert where the entrance to the Lanayru Mining Facility is located, Fi will enable the ability to place up to five beacons on the map.

The Sacred Tears also emit beacons when Link collects a Light Fruit or when he is being chased by a Guardian in the Silent Realms.

Zelda Wii U
In Zelda Wii U, Beacons can be placed in first person perspective, appering as a green light on screen. Whe the Beacon is placed, it will be shown in the map as an X. Beacons can be used to guide Epona through the overworld, as she rides automatically to where the Beacon was placed.