The skin is an amazing structure. Forming a barrier between our tissues and the world that we live in. Making us waterproof and keeping water in. Protecting us against UV light but playing a part in Vitamin D synthesis. Protecting deeper tissues from injury and containing nerve endings that allow us to detect temperature, pain, as well as the texture of surfaces that we touch. Most importantly, however, it provides a fantastic barrier to infectious agents: we are constantly under attack but the skin architecture, tears and saliva protect us.