Behavioral simulation employs a high level of abstraction to model the design. A behavioral design might, for example, contain high-level operations, such as a four-bit addition operator (this is not an adder, as in a structural design), without containing specifics on how the design will be implemented. Synthesis tools then take these behavioral designs and infer the actual gate structures and connections to be used, generating a netlist description.
Behavioral simulation is performed using a pre-synthesis Hardware Description Language (HDL) description of the design. Of the three simulation methods (behavioral, structural, and timing), behavioral simulation runs the fastest but provides the least design information.
Behavioral simulation allows you to verify syntax and functionality without timing information. During design development, most verification is accomplished through behavioral simulation. Errors identified early in the design cycle are inexpensive to fix compared to functional errors identified during silicon debug. After the required functionality is achieved, structural and timing simulation methods can be implemented to obtain more detailed verification data.