Vegetarianism is a conscious decision not to eat meat and other animal products.
Vegetarianism is the principled refusal to eat meat. The ancient Greek philosopher Pythagoras (c. 570-c. 495 BCE), who required members of his philosophical society to abstain from eating meat, is often viewed as the first important vegetarian. Before the word “vegetarian” was coined in the 1840s, non meat-eaters were often called “Pythagoreans.”
What is wrong with eating meat? Vegetarians have offered various criticisms for the practice, contending that eating meat is cruel (often, from the twentieth century onward, citing the methods of industrial meat production), unethical (often citing recent work in practical ethics, particularly by Peter Singer), unhealthy (often citing the fact that vegetarians tend to be less obese and less likely to die from ischemic heart disease), unnatural (often claiming, wrongly, that prehistoric humans subsisted on a vegetarian diet), environmentally unfriendly (often citing the relative inefficiency of meat production), and in conflict with the tenets of religious faith (sometimes citing reincarnation, as with the ancient Pythagoreans and several modern Hindu sects).
There are also different degrees of vegetarianism: for example, ovo vegetarians will eat eggs, lacto vegetarians will eat milk, and ovolacto vegetarians will eat eggs and milk, whereas vegans forego all products derived from animals and fruitarians furthermore forego all plant foods that involve killing the plant, eating only fruits, nuts, and seeds. Vegetarianism is typically associated with a similar refusal to use products derived from animals, such as leather and wool.
The modern vegetarian movement is dated to 1847, when the Vegetarian Society was founded in Great Britain. In Western countries, vegetarianism has been increasing since the 1960s, and due to continuing and intensifying ethical and environmental concerns, it is likely to flourish in the future.