Striae, commonly known as stretch marks, are linear scars that appear on the skin when it is stretched rapidly due to factors like pregnancy, weight gain, or growth spurts. They often start as red, purple, or dark brown lines and gradually fade to a lighter color over time. Striae can occur on various parts of the body, including the abdomen, thighs, and breasts. These marks are caused by the tearing of the dermis, the middle layer of skin, as it struggles to keep up with rapid changes. While striae are not harmful and do not pose any health risks, they can affect an individual's self-esteem. Treatments like creams and laser therapy may help improve their appearance.