Two major types:

1. Innate (Inborn)
2. Adaptive
   • Natural
     • Passive (e.g., through the placenta)
     • Active (e.g., through infection)
   • Artificial
     • Passive (e.g., through serotherapy)
     • Active (e.g., through vaccination)

1. Active Natural Immunity

• Develops slowly through contact with infections.
• Long-term.
• Antigen-specific.

2. Passive Natural Immunity

• Develops immediately.
• Temporary.
• Affects all antigens to which a mother has immunity (e.g., from mother to child via the placenta).

3. Passive Artificial Immunity

• Develops immediately.
• Temporary.
• Achieved through the injection of gamma globulin from another individual.

Differences Between Natural and Artificial Immunity

• Natural: Develops as a result of exposure to an antigen. Long-term.
• Artificial: Introduced into the body through injection. Typically short-term.