Our body defenses help ward off damage and disease. Together these defenses make up our immune system. Functionally, the immune system can be divided into the innate and adaptive. The Innate immune system is our non-specific first line of defense and is functional already at birth. The Adaptive immune system is specific and involves recognition of foreign bodies once they breached the innate immunity defenses. The Adaptive immunity is constantly upgrading itself by learning. The immune system plays a key role in nearly all diseases and infections, but can become an unwelcome player in autoimmune diseases, hypersensitivity and some allergies.