In order to scry, one must have a scrying crystal and a map, though a globe may also function as a scrying tool. Additionally, Billie Jenkins invented a way to scry using a crystal in combination with a computer.
Scrying is achieved by holding a crystal over a map. Once an object or being is located, the crystal will begin swinging, which will increase the closer it gets to the target. When the location is pinpointed, the crystal will drop down on the map. Scrying is more likely to be successful when an item belonging to or connected to the target is used.