Vaccination is a process of introduction of vaccine in the body. Vaccine term was taken from the word vacca which means cow in latin and first vaccine was prepared by Edward Jenner. It helps in the development of immunity, immunity which is developed by vaccination is known as adaptive immunity or acquired immunity .e.g Vaccination against polio, Smallpox, Hep. B, Pneumonia, Typhoid etc. Vaccination can be done by one of the three methods by injection or by oral or by aerosol. Vaccine can be a drug because it fulfills all the criteria of drug. Vaccines are more helpful and cost effective public health measures that prevent many diseases, such as small pox, chicken pox, rabbis and many more diseases.

Vaccines are not occurring naturally they are prepared in the laboratory. When vaccines are introduce in our body they produces antigenic response, and antibody starts work against antigen, known as primary immune response.  Antibodies are protein molecule produced in our body against antigen. There are many types of antibodies one of them is memory cell which is responsible for secondary immune response of immune system. Secondary immune response is the response of our immune system when the same antigen attacks again then our antibody produces rapidly antibody and kill them.  Antigens are foreign particles when enters in our body they produces immune response, these antigens can be a living thing like a protozoa, a virus, a bacteria or a non living thing like a dust particles or a pollen etc.

Vaccines prevents many diseases therefore children are vaccinated for many diseases, children are vaccinated because they have weak immune system at the time of birth or up to age of 2 years. At the time of birth and up to six months so vaccines are given to the baby e.g. HEp.B, Tetanus are given just after the birth of child. After that in the interval of some time period they are vaccinated. Some vaccinations are of one time while some are of 2, 3 and 4 times, which gradually increase immunity of the child. Any person of any age can be vaccinated.

Vaccination is also known as immunization, since it provides immunity against diseases.