With constantly changing opinions on what foods are the healthiest, and what foods we should be avoiding, there are new diets emerging on a regular basis. From fad diets, to weight-loss plans, to entire lifestyle changes, it can be hard to keep track of which is which. Even three of the longest-standing, most common, and most well-known diets are continuously confused with each other. Everyone knows at least one vegetarian (a term used for over 150 years), a vegan, or a pescatarian, but do we all know what those terms really mean? Knowing the difference is important for two major reasons: The first reason is that calling one diet (or lifestyle) the wrong term is just that. Wrong. The second reason is that confusing someone's dietary restrictions could be dangerous. If a vegetarian is fed fish because a cook/friend/chef assumes incorrectly that vegetarians eat fish, that person could become sick, especially if there is an allergy involved.