Time-domain reflectometry (TDR) is a technique used to determine the characteristics of electrical cables and other transmission lines. It works by sending a short pulse of electrical energy down the cable and measuring the time it takes for reflections to return. These reflections can indicate the presence of faults, such as breaks or short circuits, along the line. TDR is commonly used in telecommunications and electrical engineering to assess the integrity of cables. By analyzing the reflected signals, technicians can pinpoint issues and evaluate the overall performance of the system, ensuring reliable communication and power transmission.