Imagine you have a toy that you really love playing with, but it's outside in the sun all the time. Over time, the toy might start to fade and lose its bright colors. This is because the sun's UV rays (which you can't even see!) can damage the toy's material and make it weaker.
Now think about plastic, which is used to make lots of things like toys, water bottles, and even parts of cars and planes! These things can also be outside in the sun and get damaged too. But scientists have found a way to protect plastic from UV rays. They add special things called UV stabilizers when they make the plastic.
UV stabilizers are sort of like sunblock for plastic. They block the UV rays from harming the plastic and help to keep it strong and looking good. It's like if you put sunscreen on your skin when you go outside to play. The sunscreen blocks some of the sun's harmful rays and helps keep your skin from getting too red and sore.
So when you see a plastic toy that still looks bright and new after being outside in the sun for a long time, it's probably because it was made with UV stabilizers to protect it.