Okay kiddo, you know how your eyes work together to see the world in 3D? Well, stereoscopy is a way to create 3D images and videos that make it look like things are popping out of the screen or going really deep into it.
So, let's imagine you have two pictures of the same thing, but from slightly different angles. When you look at these pictures, your left eye sees one picture and your right eye sees the other. This is like a trick for your brain, because it puts these two pictures together to create a 3D image that looks like it's coming out of the screen.
Movie theaters and TVs can do this too! They use special glasses that show one picture to your left eye and another picture to your right eye. The glasses help your eyes work together to create a 3D image on the screen.
So, that's stereoscopy! It's like magic for your eyes that makes things look like they're really in front of you. Cool, right?