The Irish Potato Famine, also known as the Great Famine or the Great Hunger, occurred from 1845 to 1849. It was caused by successive failures of the potato crop due to a disease called late blight, caused by the water mold Phytophthora infestans. This period was devastating for Ireland, leading to about one million deaths from starvation and disease, and about two million people emigrating from the country. The famine drastically reduced Ireland's population from nearly 8.4 million in 1844 to around 6.6 million by 1851 and had long-lasting social and economic effects on the country.