Okay kiddo, so imagine you love to paint pictures but you only have a small canvas to work on. Sometimes you want to paint something in the front of the picture and other times you want to paint something in the back of the picture. But you only have one layer to work with so you don't know how to make everything look right.
That's sort of what happens in computer graphics too. When you want to draw a 3D picture on the computer, you need to figure out how to show the things in the back of the picture behind the things in the front of the picture. It's like you need to find a way to have more than one layer to paint on.
That's where a-buffer comes in. A-buffer is a special technique that computer graphics use to help manage having multiple layers when drawing a picture. It's kind of like you have a special invisible shelf that you can put your paintings on so they're all layered nicely.
A-buffer works by storing all the information about different parts of the picture in something called a buffer. But instead of just having one layer like a regular buffer, a-buffer can have multiple layers. This means you can have different parts of the picture stored on different shelves in the buffer.
When a computer wants to show you the picture, it looks at all the different parts stored in the a-buffer and decides which ones should be in the front and which ones should be in the back. It then paints the picture layer by layer in the correct order so everything looks good and not jumbled up.
So basically, a-buffer is like a special way for computers to keep track of lots of different parts of a 3D picture so it looks right when you see it on the screen.