A pendulum is basically something hanging from a string or a chain (you can even use a pencil tied to a string) that is moved by gravity and energy.
The pendulum is used to access your unconscious and unlock your potential to tell the future, everyone can use a pendulum accurately with a lot of practice (much like practicing an instrument) this is because it takes a lot of mental energy. (for me it has taken 6 years)
The pendulum swings in different directions for everyone for me for example when it swings clockwise it means yes and when it swings side to side it means no.
Accuracy, how accurate is it really? It all depends on how calm you are and how relaxed you are. In order to find out how accurate it is use a chart that has different percents 0,10,20,30,40,50,60,70,80,90 and 100 and the pendulum should only be used when its at least 70 percent accurate.
Accuracy chart: