Stretch marks, also known as striae, are narrow streaks or lines that can appear on the skin when it is stretched rapidly. They often occur during periods of significant growth, such as during puberty, pregnancy, or rapid weight gain. The skin's elastic fibers can break, leading to these marks, which may initially appear red, purple, or dark brown before fading to a lighter color. While stretch marks are common and generally harmless, they can be a cosmetic concern for some individuals. They can develop on various parts of the body, including the abdomen, thighs, hips, and breasts. Various treatments, such as creams and laser therapy, are available to help reduce their appearance.