coverage as applied to hardware verification languages refers to the collection of statistics based on sampling events within the simulation. coverage is used to determine when the device under test (dut) has been exposed to a sufficient variety of stimuli that there is a high confidence that the dut is functioning correctly. note that this differs from code coverage which instruments the design code to ensure that all lines of code in the design have been executed. functional coverage ensures that all desired corner and edge cases in the design space have been explored.