What is thermal paper?

The one downstairs is too complicated, and you don't understand those technical terms, which is of little value!

I will give you the simplest explanation.

I wonder if you have any thermal paper at hand? If there is, you will leave a black spot on the paper with your nails. This is thermal paper. Another example is the restaurant (a little more formal, such as Haidilao and Doulaofang). Every time you order a paper list, it is also heat-sensitive paper. When the waiter serves food, he will cross off one with his fingernails, indicating that the food has been served (most restaurants use this paper, but it is not excluded that there are many, but few,,).