What is the biggest role of a resistor

If a resistor has a resistance value close to zero ohms (e.g., a large cross-section wire between two points), the resistor has no resistance to current flow, the circuit in parallel with such resistors is shorted and the current flow is infinite. If a resistor has infinite or very large resistance, then the circuit connecting the resistor in series can be regarded as an open circuit and the current will be zero. A resistor commonly used in industry is somewhere between the two extremes, it has a certain resistance and can pass a certain amount of current, but not as much current as it would in a short circuit. The current limiting effect of a resistor is similar to that of a small diameter pipe connected between two large diameter pipes to limit the flow of water. Resistance, English name resistance, usually abbreviated as R, is a basic property of conductors and is related to the size, material and temperature of the conductor. Ohm's law says, I=U/R, then R=U/I, the basic unit of resistance is ohm, which is represented by the Greek letter "Ω", which has this definition: When a voltage of one volt is applied to a conductor, a current of one ampere is generated the corresponding resistance value. The main function of a resistor is to block the flow of current. In fact, "resistance" refers to a property, and the resistance commonly referred to in electronic products refers to a component such as a resistor. Ohm is often abbreviated as ohm. Commonly used units to express the resistance value of a resistor are kiloohms (kΩ), megohms (MΩ), and milliohms (mΩ).