Terminologies related to immunization like vaccination, immunization, seroconversion, seroprotection, live vaccines, inactivated vaccines, toxoids, capsular polysaccharide vaccine, subunit vaccine, conjugate vaccine are explained. The various immunization schedules like UIP, IAP, ACIP and vaccination in special circumstances like preterm infant, on corticosteroid therapy, awaiting splenectomy, adolescents, etc. are detailed. The various adverse effects of vaccines like anaphylaxis, hyporesponsive hypotensive episode, incessant cry, toxic shock syndrome, lymphadenitis, abscess, local reactions, fever and seizures are summarized in a table. Maintenance of cold chain, cold chain equipments like ILR, Walk in freezer and cold room, cold boxes, vaccine carriers, day carrier, ice packs, vaccine vial monitor, Dial thermometer and vaccine storage in a refrigerator are elaborated. Terms like T vaccines, First in first out (FIFO), First expiry first out (FEFO) are also explained.