A resistor is an electronic component that limits the flow of electric current in a circuit. It is used to control voltage and current levels, ensuring that other components function correctly without being damaged by excessive current. Resistors come in various types, including fixed, variable, and specialty resistors, each serving different purposes in electronic designs. In addition to their primary function, resistors also play a crucial role in setting bias points in transistors and creating voltage dividers. They are essential in both analog and digital circuits, making them fundamental components in devices ranging from simple gadgets to complex computers.