Fine lines are caused by lax, sagging skin due to aging. Fine lines and wrinkles are always linked together, but wrinkles are more complex than fine lines. Fine lines are usually between one and two millimeters in depth. Wrinkles are lines that are deeper than 2mm in depth. In fact, fine lines are the earliest signs of aging which affect women in their 30's and 40's. As you age, collagen breaks down and repeated movements in the skin cause deeper wrinkles. There are many over the counter skincare products that will help reduce the appearance of fine lines and wrinkles.