What is the primary function of an LED?

The primary function of an LED, or Light Emitting Diode, is to serve as an indicator light. LEDs are designed to emit light when an electric current passes through them, making them ideal for use as indicators in various electronic devices. For example, they are commonly used to show the operational status of a device, such as whether it is powered on or off, or to provide visual feedback in circuits.

In applications, the brightness and color of the emitted light can be controlled by varying the current that flows through the LED, which is why they are often used in displays and signaling. This functionality is central to many electronic applications, including signage, backlighting, and status indicators in household and industrial equipment.

While other options mention functions like sound emission, current regulation, or energy storage, these do not reflect the fundamental role of an LED, which is primarily focused on light emission. Therefore, serving as an indicator light stands out as the main function of an LED.