A sequence preset is a pre-configured template that defines the settings for a new sequence in Premiere Pro. These settings include the frame rate, resolution, pixel aspect ratio, and other parameters that determine how your video will be displayed. Sequence presets are designed to match the specifications of various video formats, such as HD, 4K, or SD, and can be used to create sequences for different types of projects, including films, television shows, commercials, and social media videos.