Verilog HDL is one of the two most common Hardware Description Languages (HDL) used by integrated circuit
(IC) designers. The other one is VHDL.
HDL’s allows the design to be simulated earlier in the design cycle in order to correct errors or experiment with
different architectures. Designs described in HDL are technology-independent, easy to design and debug, and are
usually more readable than schematics, particularly for large circuits.
Verilog can be used to describe designs at four levels of abstraction:
(i) Algorithmic level (much like c code with if, case and loop statements).
(ii) Register transfer level (RTL uses registers connected by Boolean equations).
(iii) Gate level (interconnected AND, NOR etc.).
(iv) Switch level (the switches are MOS transistors inside gates).
The language also defines constructs that can be used to control the input and output of simulation.