Binary digital circuits are electronic circuits that operate using two distinct states, typically represented as 0 and 1. These circuits form the foundation of modern computing, as they process and store information in binary form. Components like transistors act as switches, allowing or blocking the flow of electrical current to represent these binary states. These circuits can be combined to create more complex systems, such as logic gates, which perform basic operations like AND, OR, and NOT. By connecting multiple gates, engineers can design adders, multipliers, and other essential components used in microprocessors and digital devices.