Generally speaking, the term 'paper' refers to both paper and cardboard. In fact, the difference between paper and cardboard is only based on their quantity (relative weight per square meter of paper surface area). Generally, paper weighing less than 200g/㎡ is referred to as paper in folk culture; Paper weighing over 200g/㎡ is called cardboard. In the past, the quantitative regulations for paper and cardboard in China were: paper with an area of less than 150 square meters; Anything above 200g/㎡ is called cardboard. The paper between 150-200g/㎡ is called cardboard (base paper). We usually refer to thin paper as paper and thick paper as cardboard. But in order to communicate information and exchange technology with foreign countries, according to the recommendations of the standard organization, the quantitative standard for distinguishing paper and cardboard has been determined to be 225g/㎡.