The skin is the largest organ of the human body. The functions of the skin are to protect us from external insults and to maintain internal homeostasis. During an individual's lifespan, there may be periods of enhanced skin vulnerability, which render the individual more prone to the development of skin problems. Critical phases are very early in life (when the skin is not fully mature), when individuals are suffering from dermatological or other systemic and chronic diseases, at advanced age, and at the end of life. The International Skin Tear Advisory Panel (ISTAP) has identified key knowledge gaps in prevention and management of skin problems in these critical phases, in order to improve practice and clinical outcomes.