Vomiting, or throwing up, is a reflex action by the body to expel substances that may be harmful. It often occurs as a protective response to get rid of toxins, infections, or irritants in the digestive tract. Vomiting can be triggered by various causes including infections like gastroenteritis, food poisoning, motion sickness, alcohol consumption, pregnancy, emotional stress, certain medications, and medical conditions involving the digestive system or brain. It helps prevent further intake of harmful substances and clears the stomach when it is irritated or overloaded.