The sticker on the back of yoga pants is often called a "brand mark" or "trademark label." It is used to display the logo of the yoga brand or manufacturer. Trademark labels usually include the brand name, trademark design or logo, and other relevant information. These labels not only help consumers identify the origin of the product, but also convey the brand's image and values. However, it should be noted that different brands of yoga pants may have different label designs and names.