Self-adhesive labels, also called sticker labels, Post-it notes, or pressure-sensitive paper, are composite materials made of paper, film, or special materials as the face material, with adhesive applied to the back and a silicone-coated release paper as the backing. After printing, die-cutting, and other processing, they become finished labels. When used, simply peel off the backing and press lightly to stick them onto various substrates, or use labeling machines to automatically apply them on a production line. Compared with traditional labels, self-adhesive labels do not require brushing glue, paste, or dipping in water, and they are completely free of pollution. They save labeling time and can be conveniently and quickly used in various situations. By using different face materials, adhesives, and backing papers, they can be made into various labels that can be applied to materials not suitable for ordinary paper labels. It can be said that self-adhesive labels are a universal type of label.