Vertex normal

A vertex normal is like a special direction that tells a computer how to make a surface look smooth and consistent. Imagine you have a big box made of little squares. When you look at each square closely, you might notice that some are facing straight up while others are at different angles. A vertex normal helps the computer know which way the square is facing so it can make the whole box look nice and smooth instead of lumpy. Just like how a map has coordinates to show where things are, a vertex normal has coordinates to show where the direction is pointing. This way, the computer can draw the right shadows and highlights on each surface to make it look realistic. Cool, right?