Immunity Immunity is the body’s ability to resist infections and defend against foreign substances, pathogens, and harmful agents. It involves a complex network of cells, tissues, and molecules that work together to recognize and eliminate invaders while maintaining tolerance to self-antigens. Types of Immunity 1. Innate Immunity 2. Adaptive Immunity Classification of Adaptive Immunity 1. Active Immunity 2. Passive Immunity Key Components of the Immune System 1. Cells 2. Molecules