A JK flip-flop is an improved version of the SR flip-flop, which solves the problem of the "invalid state" in the SR flip-flop. It's a fundamental memory element in digital electronics and is widely used because of its versatility.

Key Features and Operation:

• Inputs: The JK flip-flop has two inputs: J and K, along with a clock signal that controls the state changes.
• Outputs: It has two outputs: Q (the main output) and Q̅ (the inverted output).
• Clock-Triggered: The state of the flip-flop changes only when a clock signal is applied (typically on a rising or falling edge of the clock).
  

  Explanation of States:

  1. J = 0, K = 0 (Hold): The flip-flop maintains its previous state, so no change occurs regardless of the clock.

  2. J = 0, K = 1 (Reset): The output Q is reset to 0, making the flip-flop output 0 (like the Reset state in an SR flip-flop).

  3. J = 1, K = 0 (Set): The output Q is set to 1, so the flip-flop holds a value of 1 (similar to the Set state in an SR flip-flop).

  4. J = 1, K = 1 (Toggle): This is the unique feature of the JK flip-flop. When both J and K are 1, the output toggles (switches) from 1 to 0, or from 0 to 1, depending on the current state.

  Clock Signal and Edge-Triggering:

  The JK flip-flop is edge-triggered, meaning it only responds to changes in the clock signal (either rising edge or falling edge, depending on the design). The outputs change only when the clock makes the appropriate transition.