What is filter paper? Most of the filter paper is made of cotton fiber

Most of the filter paper is made of cotton fibers, which are made by different methods according to different uses. Because its material is made of fiber, there are numerous small holes on its surface for liquid particles to pass through, while larger solid particles cannot. This property allows the separation of liquid and solid substances that are mixed together. The function of filter paper in coffee making is to filter out coffee grounds with filter paper in the process of making drip filter coffee, so that coffee grounds can be separated from coffee liquid. (this article is reproduced)