Asynchronous Inputs:
The S-R (Set-Reset), J-K (Jump-Kill), and D (Data) inputs are known as synchronous inputs. These inputs are commonly used in digital circuits, such as flip-flops and memory elements, to control the behavior and state of the circuit.

Synchronous Inputs:
The term "synchronous" refers to the fact that these inputs are synchronized with a clock signal. In synchronous circuits, the clock signal is used to control the timing and sequencing of the circuit's operations. The state of the circuit is only updated when a clock edge occurs, ensuring that all changes happen simultaneously.

Differences between Synchronous and Asynchronous Inputs:
1. Timing: Synchronous inputs are synchronized with the clock signal and change their state only at specific clock edges. Asynchronous inputs, on the other hand, can change their state independently of the clock signal.

2. Simultaneity: Synchronous inputs ensure that all changes happen simultaneously, as they are updated together during the clock edge. Asynchronous inputs do not guarantee this simultaneous behavior and can introduce timing hazards or glitches.

3. Stability: Synchronous inputs are typically edge-triggered, meaning they are stable and will not change their state until the next clock edge. Asynchronous inputs can be level-triggered, meaning their state can change and propagate through the circuit at any time.

4. Design Complexity: Synchronous designs are generally easier to analyze and implement since the timing behavior is well-defined and predictable. Asynchronous designs require additional considerations, such as handling metastability issues and ensuring proper timing constraints.

Importance of Synchronous Inputs:
Synchronous inputs provide a structured and predictable way to control the operation of digital circuits. By using a clock signal, the circuit can be designed to perform specific actions at specific times. This allows for more reliable and consistent behavior, especially in complex systems where numerous signals need to be coordinated.

In contrast, asynchronous inputs can introduce unpredictable behavior and can be challenging to analyze and debug. They are typically used in specialized cases where specific timing requirements or functionality necessitate their use.

In conclusion, S-R, J-K, and D inputs are called synchronous inputs because they are synchronized with a clock signal and change their state only at specific clock edges. Synchronous inputs provide a structured and predictable way to control the behavior and timing of digital circuits, ensuring reliable and consistent operation.