Vegetarianism is a form of diet that excludes animal products in diet. Some vegetarians may exclude only meat products while others may exclude animal products in any form such as cakes that use eggs and medicines such as fish oil. A very strict form of vegetarianism is veganism that excludes animal products of all form from diet. This also includes honey and animal products. Many vegetarians are in reality semi-vegetarians that partake of an occasional meal that includes fish or poultry. Religion is the most common reason for following a vegetarian diet.