Everyone wants to retain their glowing skin forever, but skin loses its glowing youthfulness naturally with increasing age. According to dermatologists, stretch marks are narrow streaks or lines on the skin with an off color hue. Rapid growth, rapid weight gain or weight loss are the main reasons of stretch marks on the skin and other causes of stretch marks include puberty, pregnancy, bodybuilding and hormone replacement therapy. Stretch marks first appear as reddish lines and the lines are usually long and thin. The affected areas are soft to the touch and the lines can appear in any pars of the body but they generally appear in places where larger amounts of fat are stored like abdomen, breasts, upper arms, underarms, back, thighs, hips and buttocks.