Magnetic cards can be divided into two types according to their structure. One is a plastic card that looks like a playing card and has a magnetic stripe similar to an audio tape stuck on the surface. Currently, we commonly use various credit cards. , such as "Great Wall Card", "Peony Card", etc. all fall into this category; the other is a magnetic card with a magnetic paint coated on the inner layer of a vinyl plastic card, which is called a PET card.