Variable resistors, also known as potentiometers or rheostats, are electrical components that allow users to adjust resistance within a circuit. This adjustment can control the flow of electric current, making them useful in applications like volume controls in audio devices or brightness settings in lights. These components typically consist of a resistive element and a movable contact, which changes the resistance as it is adjusted. By altering the position of the contact, users can fine-tune the electrical characteristics of a circuit, providing flexibility in various electronic devices and systems.