The Black Death, or the Black Plague, was one of the deadliest pandemics in human history, widely thought to have been caused by a bacterium named Yersinia pestis (Bubonic plague),but recently sometimes attributed to other diseases.

It began in Central Asia and spread to Europe during the 1340s. The total number of deaths worldwide from the pandemic is estimated at 75 million people; approximately 25-50 million of these deaths occurred in Europe. The Black Death is estimated to have killed 30% to 60% of Europe's population. It may have reduced the world's population from an estimated 450 million to between 350 and 375 million in 1400.

Bubonic plague is thought to have returned to Europe every generation with varying virulence and mortalities until the 1700s.During this period, more than 100 plague epidemics swept across Europe.n its return in 1603, the plague killed 38,000 Londoners. Other notable 17th century outbreaks were the Italian Plague of 1629-1631, the Great Plague of Seville (1647-1652), the Great Plague of London (1665–1666),the Great Plague of Vienna (1679). There is some controversy over the identity of the disease, but in its virulent form, after the Great Plague of Marseille in 1720–1722, the Great Plague of 1738 (which hit eastern Europe), and the 1771 plague in Moscow it seems to have disappeared from Europe in the 19th century.

The 14th century eruption of the Black Death had a drastic effect on Europe's population, irrevocably changing Europe's social structure. It was a serious blow to the Roman Catholic Church, and resulted in widespread persecution of minorities such as Jews, foreigners, beggars, and lepers. The uncertainty of daily survival created a general mood of morbidity, influencing people to "live for the moment", as illustrated by Giovanni Boccaccio in The Decameron (1353).