A process of navigation by which a destination is approached by keeping some navigation parameter constant. In its early uses, the most commonly chosen parameter was the relative bearing from the vehicle to destination as determined from a signal emitted at or near the destination point. The vehicle then steers to travel in the direction of its destination. The signal can be of many forms, ranging from a visual image to a radio wave or even an odor. This simple form of homing requires minimal on-board equipment, but the path taken by the vehicle over the Earth's surface is influenced by vehicle drift due to winds, currents, or other causes.