A flip-flop is a fundamental building block of digital electronics used to store binary information. It belongs to the category of bistable multivibrator circuits, meaning it has two stable states. These states are often referred to as "1" and "0," representing binary values.
SR Flip-Flop (Set-Reset Flip-Flop):
Construction, excitation table:

Consists of two cross-coupled NAND gates or NOR gates.
Working Principle:
Two inputs: Set (S) and Reset (R).
When S=1 and R=0, the flip-flop sets, making Q=1 and Q'=0.
When R=1 and S=0, the flip-flop resets, making Q=0 and Q'=1.
When both S and R are 0, the flip-flop maintains its previous state.
When both S and R are 1, the flip-flop enters an undefined state.
Implementation:
Constructed using NAND or NOR gates.
Application:
Used for memory storage and state control in digital systems.
D Flip-Flop (Data Flip-Flop):
Construction:

Typically constructed using an SR flip-flop with an inverter (NOT gate) on the input.