Type IV refers to a classification system used in various fields, including biology and psychology. In biology, it often describes a specific type of hypersensitivity reaction, where the immune system responds to an antigen in a delayed manner. This can lead to conditions like contact dermatitis, where skin becomes inflamed after exposure to certain substances, such as poison ivy. In psychology, Type IV can refer to a personality type characterized by emotional depth and introspection. Individuals with this type may be sensitive and creative, often expressing themselves through art or writing. They tend to seek deeper connections with others and may be drawn to exploring their inner thoughts and feelings.