Vegetarianism is the practice of abstaining from the consumption of meat (red meat, poultry, seafood, insects, and the flesh of any other animal). It may also include abstaining from eating all by-products of animal slaughter.

Vegetarianism may be adopted for various reasons. Many people object to eating meat out of respect for sentient animal life. Such ethical motivations have been codified under various religious beliefs as well as animal rights advocacy. Other motivations for vegetarianism are health-related, political, environmental, cultural, aesthetic, economic, taste-related, or relate to other personal preferences.

There are many variations of the vegetarian diet: an ovo-lacto vegetarian diet includes both eggs and dairy products, an ovo-vegetarian diet includes eggs but not dairy products, and a lacto-vegetarian diet includes dairy products but not eggs. As the strictest of vegetarian diets, a vegan diet excludes all animal products, including eggs and dairy (and even extends to abstain the use of any animal derived product).

Maintenance of a vegetarian diet can be challenging. While avoidance of animal products may support health and ethical concerns, dietary supplements may be needed to prevent nutritional deficiency if all such products are shunned, particularly for vitamin B12. Packaged and processed foods may contain minor quantities of animal ingredients. While some vegetarians scrutinize product labels for such ingredients, others do not object to consuming them, or are unaware of their presence.