Flip-flops
A device that changes its output state only when a clock signal makes a specified transition (either low to high or high to low) is referred to as an edge-sensitive device. Flip-flops are similar to latches, with the key difference being that the output of a flip-flop changes in response to a clock edge rather than responding continuously to its input signal while enabled.
The positive edge-triggered D flip-flop is a popular digital circuit component used in a wide variety of applications. The D flip-flop typically includes set and reset input signals that perform the same functions as in the SR latch. This flip-flop has a D input that functions just like the D input of the gated D latch. Instead of an enable input, the D flip-flop has a clock input that triggers the transfer of the D input to the Q output and, with inversion, to the 
output on the clock’s rising edge. Other than within a very narrow time window surrounding the rising edge of the clock signal...
