Wrinkles pertain to the lines & folds which form in your skin. Few wrinkles may become deep crevices and may be particularly apparent around your eyes, mouth & neck. They are a natural component of aging, are most distinct on sun-exposed skin, such as the face, neck, hands & forearms.
They are formed by the following reasons:
Age
With advancing age, your skin automatically becomes less elastic and more fragile. Decreased generation of natural oils dries your skin & changes it appearance to more wrinkled. Lipids in the lower folds of your skin diminishes. This leads to loose, saggy skin & more clear cut lines and crevices.