Okay kiddo, so you might have heard of WiFi. It's like magic internet that comes through the air to your phone or tablet, right? Well, that WiFi needs something to make it happen - that's where the modem comes in.
Think of it like a translator between the internet world and your home. It takes the signal from your internet service provider (like Comcast or AT&T) and turns it into something your computer or phone can understand. Just like how you need a grown-up to help you understand big words sometimes, the modem helps your devices understand internet.
The modem also sends signals back out to the internet so you can watch videos, play games, or do your homework. So, you see, it's a pretty important piece of technology!