Vaccines have been used in the fight against diseases from the past until the present. Vaccines are of great importance, especially in the fight against viruses. It is very important for the health sector to produce new vaccines for various diseases using different techniques. The first attempt at vaccine production started in the fifteenth century and has become an important therapeutic. This chapter briefly focuses on the history of vaccine production, on what is the immunological base of vaccines, how they work, and their importance. As a result, this chapter is an introduction to the other 16 chapters and provides general information about vaccines.