What Is RTL?

Register Transfer Level (RTL) describes hardware in terms of registers, the combinational logic between them, and how data moves from register to register on clock edges.

Registers hold current values. Combinational logic uses those values and current inputs to compute next values. On a clock edge, destination registers capture the computed results. Between edges, the registers hold steady while the logic continues to respond to its inputs.

This view gives a design both structure and time. The structure is the path from source registers, through logic, to destination registers. The time comes from the clock edges that decide when newly computed values become stored state.

RTL does not mean “any Verilog that simulates.” A good description makes the intended storage, computation, and clocked movement clear. Simulation then checks whether those choices produce the required behavior over time.