The aim of this lecture is to present on what is food born illness. Illness resulting from eating food contaminated with a bacteria or virus. May cause outbreaks where many people become sick, with the same illness at the same time (about 10% of a population). Usually contaminated food comes from a location away from home (restaurant, baseball game etc.). The tracking of outbreaks of illness (not always food illness) to discover where the original source of contamination came from.