A wrinkle, also known as a rhytide, is a fold, ridge or crease in the skin. When we're young, we don't have wrinkles because the skin does a great job of stretching and holding in moisture. As we age, our skin loses moisture and elasticity, making it prone to wrinkles. Dermatologists have many tools for tackling those little lines that mark the passage of time. They include prescription creams, chemical peels, and Botox.