1. Remember that any current injected into a system must return to the source. 2. It will do so through the path of least impedance, which in most cases means the path of least inductance. 3. Subsequently, the return current path is not fixed, but it varies with frequency. 4. Furthermore, in systems where there exist a multitude of return current paths, different amounts of the return current will flow along each path. 5. Any discontinuity in the return current path degrades the signal integrity.