What is the purpose of a set screw for a faucet handle and how is it used in the installation process?

A set screw for a faucet handle is used to secure the handle onto the faucet stem. It is typically a small screw that is tightened against the stem to hold the handle in place. During installation, the set screw is inserted into a hole on the handle and tightened using a screwdriver to ensure the handle stays securely attached to the faucet.