Normal vector

A normal vector is like a special friend that helps us figure out directions. Imagine you are coloring on a piece of paper and you draw a straight line. Now, you have a special friend that can tell you which way is up and which way is down just by standing right on top of the line you drew. This special friend is your normal vector. It points in a direction that's perpendicular to the line you drew.

So, if you're walking on the sidewalk, and you come up to a curb, your normal vector for that curb would point straight up, because the curb is standing up straight, you know? It's telling you which way is "normal" for that surface.

Now, let's say you have a surface that's not flat, like a hill. You might have different normal vectors depending on which part of that surface you're standing on, because the hill is tilting in different directions in different places. So, your special friend, the normal vector, helps you figure out which way is "normal" for each specific point, because it points straight out from the surface, giving you a reference direction.