Light pen

A light pen is like a magic wand used to interact with a computer or a TV screen. When you touch the screen with the pen, it sends a signal to the computer or TV telling it where you touched.

The pen is called a "light" pen because it has a special light on the end that glows when you touch the screen. The computer or TV can recognize where you touch because the light pen sends a signal that the computer or TV can understand.

It's a really cool gadget that was more popular a long time ago, but now we usually use touch screens or a mouse to interact with our computers and TVs.