Here's why:

* Insulators: Do not allow electricity to flow through them easily. Examples: rubber, glass, plastic.

* Conductors: Allow electricity to flow through them easily. Examples: copper, silver, gold.

* Semiconductors: Have properties between insulators and conductors. They can conduct electricity under certain conditions, like the presence of an electric field or light.

LEDs (Light Emitting Diodes) are made of semiconductor materials. The specific type of semiconductor used determines the color of light emitted by the LED. The semiconductor material allows the flow of electricity in one direction, and when current flows through the LED, it emits light.