Barrier grid animation is when you use an alternating grid of black and white lines that moves in front of a picture or video. The grid moves back and forth really fast, and it tricks your brain into seeing the picture or video as if it has depth.
Think of it like looking at a picture through a fence with alternating white and black bars. As you move the fence back and forth really fast, the picture seems like it's jumping off the page, even though it's just flat.
Stereography is a way of creating a 3D image or video. It uses two different images, one for each eye, that are slightly offset from each other. When you look at these images through special glasses, your brain combines them to make one 3D image.
It's kind of like seeing two slightly different pictures with each eye, and your brain puts them together to make one image with depth, like looking at something in real life.
Barrier grid animation and stereography both use tricks to make pictures and videos seem like they have depth, making them more exciting and lifelike to look at.