A logic device that changes its output state in response to a High or Low level of clock signal

The device you're referring to is known as a Flip-Flop. A Flip-Flop is a type of logic device that changes its output state in response to a high or low level of a clock signal.

Here's a step-by-step explanation:

1. A Flip-Flop is a basic form of memory storage element used in digital circuits. It's a bistable device, meaning it has two stable states - it can store either a '0' or a '1'.

2. The output state of a Flip-Flop is changed or "flipped" from one state to another by applying a clock signal. This clock signal is simply a periodic square wave that oscillates between a high and a low level.

3. When the clock signal goes from low to high (rising edge), or from high to low (falling edge), it triggers the Flip-Flop to change its output state.

4. The exact behavior of the Flip-Flop - whether it changes state on a rising edge or a falling edge, and what the new state will be - depends on the type of Flip-Flop. There are several types, including SR (Set-Reset), D (Data), JK, and T (Toggle) Flip-Flops, each with its own unique behavior.

5. The ability of Flip-Flops to maintain a state until changed by the clock signal makes them very useful in digital electronics, where they serve as the building blocks for counters, shift registers, and memory units.