A set-top box is a device that connects to a television and receives digital signals, allowing users to access various content such as cable TV, streaming services, and on-demand videos. It acts as a bridge between the TV and external sources, converting the signals into a format that the television can display. These devices often come with features like recording capabilities, interactive menus, and access to apps. Popular examples of set-top boxes include Roku, Apple TV, and Amazon Fire TV. They enhance the viewing experience by providing a wide range of entertainment options in one place.