What electronic component allows current to flow in only one direction?

A diode is a fundamental semiconductor device designed to act as a one-way valve for electrical current. It has high resistance in one direction and very low resistance in the other, which is why it is often used to convert alternating current (AC) to direct current (DC) in a process called rectification. Distractors like resistors and fuses are incorrect because they allow current to flow equally well in both directions. A resistor simply opposes current flow to a specific degree, while a fuse is a safety device that breaks the circuit if the current gets too high, regardless of the current's direction.