A "gaffer" is a key member of a film or television production crew, responsible for the lighting on set. They work closely with the director of photography to create the desired mood and atmosphere for each scene. The gaffer manages the lighting team and oversees the setup, adjustment, and operation of lighting equipment. In addition to lighting, the gaffer also ensures safety on set by managing electrical equipment and cables. This role is crucial for achieving the visual style of a production, making the gaffer an essential part of the filmmaking process alongside other crew members like the director and cinematographer.