The uneven pigmentation of skin resulting from sun exposure, where certain areas remain lighter due to being shielded by clothing or accessories, creates a noticeable contrast known as demarcation lines. An example of this is the distinct difference in skin tone observed between the upper arm, exposed to the sun, and the skin covered by a t-shirt sleeve.
Addressing this uneven skin tone contributes significantly to aesthetic appearance and self-confidence. Historically, societies have employed various methods to even out skin tone, ranging from natural remedies to more advanced dermatological procedures. Achieving uniform skin color is perceived as a sign of health and careful self-care in many cultures.