The Black Death, also known as the Great Plague, swept Europe during the mid-14th century and is considered one of the most devastating pandemics in human history. It is estimated that 75-200 million people lost their lives. Synonyms for the Black Death include the Bubonic Plague, Pestilence, and the Black Plague. It is believed that the disease was caused by the bacterium Yersinia pestis carried by fleas on black rats, and spread rapidly through trade routes in Europe. The Black Death had a profound impact on European society, causing widespread panic, economic turmoil, and permanently altering the course of history.