dR, or "differential resistance," refers to the change in voltage across a device divided by the change in current flowing through it. It is an important concept in electronics, helping to understand how components like resistors and diodes behave under varying electrical conditions. In practical terms, dR can indicate how a device will respond to changes in input. For example, in a diode, the differential resistance can vary significantly depending on the operating point, affecting how efficiently it conducts electricity. Understanding dR is crucial for designing circuits and optimizing performance.