Think about a simple room. When you turn on a light, everything becomes visible. The walls, the furniture, the floor—it all comes to life. Without light, the room is just darkness. The same idea applies to your 3D scenes in Three.js. Without light, your objects are there, but they feel flat and hard to see. Light is what makes your scene look real. It helps you see shapes, colors, and details. In Three.js, you can add different types of lights, just like in real life. For example: