Which is used for storing the one-bit digital data? 

Flip-Flop

• A flip-flop is the basic storage element in sequential logic.
• A flip-flop is a device that stores a single bit (binary digit) of data.
• The stored data can be changed by applying varying inputs.
• Flip Flops are edge-triggered while the latch is level-triggered.
• Flip Flops are of 4 types: SR, JK, T, and D flip-flops.

​Register

• A Register is a collection of flip-flops.
• For storing n-bit data, a register comprising of n number of flip-flops is used.

GATE

• A logic gate is a device that acts as a building block for digital circuits.
• They perform basic logical functions that are fundamental to digital circuits. 
• Example: AND, OR, NOT, NAND, NOR, XOR, XNOR