Linear polarization

Linear polarization is kind of like making sure a ball only rolls in one direction. Imagine a ball rolling on a hill - sometimes it might roll left, sometimes it might roll right, and sometimes it might roll straight down. But if we attached a special piece to the ball that only lets it roll in one direction, then it will always roll that way no matter how bumpy or twisty the hill is.

Now, replace the ball with light, which is made up of little particles called photons. Normally, these photons bounce and wiggle all over the place, so the light they make goes in lots of different directions. But if we use a special filter, kind of like the ball's special piece, we can make all the photons go in the same direction. This is called "linear polarization" because the light waves - which are made up of lots of photons - all move in the same straight line.

So, imagine you have a toy car with headlights on it. If we point those headlights at a plain white wall, the light from the headlights will go everywhere and make the whole wall light up. But if we put a special filter in front of the headlights that only lets the light waves move in one straight line, then the light from the headlights will only make a straight line of light on the wall. That's linear polarization!