A set-top box is a device that connects to a television and an external signal source, such as a cable or satellite service. It decodes and converts digital signals into a format that can be displayed on the TV screen. Set-top boxes often provide additional features like recording shows, accessing streaming services, and offering interactive content. These devices can vary in functionality, with some supporting high-definition (HD) or 4K video, while others may include features like video on demand or smart TV capabilities. Many households use set-top boxes to enhance their viewing experience and access a wider range of entertainment options.