Structure-based testing techniques (which are also dynamic rather than static) use the internal structure of the software to derive test cases.
They are commonly called 'white-box' or 'glass-box' techniques (implying you can see into the system) since they require knowledge of how the software
is implemented, that is, how it works. For example, a structural technique may be concerned with exercising loops in the software. Different test cases
may be derived to exercise the loop once, twice, and many times. This may be done regardless of the functionality of the software.