The pendulum is a tool that has been for hundreds of years to divine answers based on the direction of its swing. Today they are used in a variety of ways, such as locating lost items on a map, identifying areas of healing needed during body layouts, or even hypnosis.
One simple way to get started with and connect to your pendulum is by holding the end of the chain and allowing the pendulum to be still before asking a yes or no question that you already know the answer to - such as your name or birthday. For some, the pendulum will swing clockwise for a "Yes" response or side to side for a "No" response.
Can also be used with a pendulum mat like this one.
Obsidian is excellent for clearing unwanted energies and use in divination