Venous thromboembolism is the formation of a blood clot in the vein. It mainly consists of 2 life-threatening conditions—deep venous thrombosis and pulmonary embolism. Deep venous thrombosis is a potentially dangerous condition with grave sequelae, the worst of which is pulmonary embolism. Venous thromboembolism can also lead to multiple other conditions with significant morbidity and mortality that include extension of thrombi, pulmonary hypertension, recurrence, and postthrombotic syndrome. An update on the epidemiology, etiology, and pathogenesis of venous thromboembolism will be reviewed in this article.