The terms inoculation, "vaccination", and "immunization" are often used synonymously to refer to artificial induction of immunity against various infectious diseases. This is supported by some dictionaries. However, there are some important historical and current differences. In English medicine, inoculation referred only to the practice of variolation until the very early 1800s. When Edward Jenner introduced smallpox vaccine in 1798, this was initially called "cowpox inoculation" or "vaccine inoculation"