Resistance measurement is the process of determining how much a material opposes the flow of electric current. This is typically done using a device called an ohmmeter, which applies a small voltage to the material and measures the resulting current. The resistance is calculated using Ohm's Law, which states that resistance (R) equals voltage (V) divided by current (I). Resistance is measured in units called ohms. Different materials have different resistance levels; for example, metals like copper have low resistance, making them good conductors, while rubber has high resistance, making it an insulator. Understanding resistance is crucial in electrical engineering and circuit design.