B-Roll is supplemental footage used in video production to enhance the storytelling of a primary narrative. It provides context, visual interest, and helps to illustrate the points being made in the main footage, often referred to as A-Roll. B-Roll can include scenes of people interacting, locations, or objects relevant to the subject matter. In interviews, B-Roll is often used to show the interviewee's environment or related activities while they speak. This technique keeps the audience engaged and can help convey emotions or themes more effectively. Overall, B-Roll is an essential tool for creating dynamic and informative videos.