Add-drop multiplexer

Imagine you have a bunch of different colored candies that you want to sort into different jars. Instead of doing it one at a time, you can use a special tool called an add-drop multiplexer.

The add-drop multiplexer is like a machine that takes in a bunch of different signals (like the different colored candies) and sorts them into different outputs (like the jars). But sometimes, you might want to add a new signal to the mix or take one out. That's where the "add-drop" part comes in. It's like adding a new candy to the sorting process or taking one out to put it somewhere else.

So, an add-drop multiplexer is a tool that helps you sort a bunch of different signals into different outputs, but also lets you add or remove signals as needed.