What is tri-state logic?

Tri-state (or 3-state) logic refers to digital circuits that have three distinct output conditions: high (logic 1), low (logic 0), and a high-impedance state (often called High-Z). In the high-impedance state, the output behaves as if it is physically disconnected from the circuit. This high-impedance state is essential for modern electronics, as it allows multiple logic devices to share a single communication bus without shorting each other out. Only the active device drives the bus with a 0 or 1, while all other devices stay in the disconnected High-Z state. Distractors mentioning ternary math or selecting impedances to match loads incorrectly describe the purpose of this third disconnected state.