A register stores several bits together so that they can represent a binary number, instruction field or other fixed-width value.

A simple $n$-bit synchronous register can be built from $n$ flip-flops sharing the same clock.

Parallel storage

Each flip-flop stores one bit:

D3 D2 D1 D0
│  │  │  │
FF FF FF FF   ← shared clock
│  │  │  │
Q3 Q2 Q1 Q0

At the active clock edge, all bits capture their inputs as one coordinated state update.

Load control

A register often includes a load or enable control. When loading is disabled, feedback routes each stored output back to its own input so the register preserves its value across clock edges.

Registers in processors

Processors use registers as small, fast storage for operands, addresses, instructions and control state. Those architectural registers are built from more detailed circuit implementations, but conceptually they provide fixed-width values that can be read and updated during instruction execution.