Dowsing is probably best known for locating water, gold, oil and other minerals. The use of the pendulum is officially considered to be a science known throughout Europe as Radiesthesia.
Anyone can do it. With using a pendulum it's not the technique that's difficult to master, but how to word the questions you want to ask.
Using a pendulum, you can find out almost anything, from where your keys are to your ancestral lineage. It is also very helpful in buying the right house for you or to see if there are any underground watercourses, ley lines, rock fissures, fault lines, geographic grids, electromagnetism or electromagnetic smog causing disturbances.