Crit'Air is a sticker that you put on your car in France. It is a way for the government to know how much pollution your car produces. Depending on how much pollution your car makes, you will get a sticker with a different color and number on it. The lower the number, the less pollution your car produces.
When you want to drive in certain cities in France, you must now have this sticker on your car. It helps authorities control the pollution levels in the city. Different cities may have different rules for the Crit'Air sticker based on the current pollution levels.
It is important to remember that Crit'Air is not a way for the government to make money or punish car owners. It is simply a way to protect the environment and ensure that people can breathe clean air. So, even if you do not like the idea of putting a sticker on your car, it is important to do it for the sake of the environment.