Blood donation is the voluntary process of donating one's blood to be used for medical purposes. It involves drawing 350ml of blood from a donor using sterile equipment to prevent infection. Donating blood takes about an hour and the body replaces the donated blood within 1-2 days. There is a high demand for blood in India but low availability, with a shortage of 400,000 units per year. Regular blood donations are needed to help accident victims, surgery patients, and premature babies who require blood transfusions.