![header-lesson-03](assets/header-lesson-03.png)

# Lesson 3: Light-Emitting Diodes (LEDs)

## What is an LED?

LEDs are diodes. A diode is an electronic component that acts like a one-way street for electricity. It only lets electric current flow in one direction and stops it from going the other way. Think of it like a valve or a gate that only opens in one direction. An LED will not illuminate if the anode (longer positive leg) is connected to the ground.

![led-diagram](assets/led-diagram.png)

The anode is the **positive terminal** marked with a (`+`) connected to the longer leg of the LED (usually indicated by a notch on the LED casing). The cathode is the **negative terminal** marked with a (`-`), connected to the shorter leg (usually indicated by a flat edge on the LED casing).