In Ireland, the Great Famine was a period of mass starvation, disease and emigration between 1845 and 1852. It is also known, mostly outside Ireland, as the Irish Potato Famine. In the Irish language it is called an Gorta Mór, meaning "the Great Hunger" or an Drochshaol, meaning "the bad times".
During the famine approximately 1 million people died and a million more emigrated from Ireland, causing the island's population to fall by between 20% and 25%. The proximate cause of famine was a potato disease commonly known as potato blight. Although blight ravaged potato crops throughout Europe during the 1840s, the impact and human cost in Ireland – where one-third of the population was entirely dependent on the potato for food – was exacerbated by a host of political, social and economic factors which remain the subject of historical debate.
The famine was a watershed in the history of Ireland. Its effects permanently changed the island's demographic, political and cultural landscape. For both the native Irish and those in the resulting diaspora, the famine entered folk memory and became a rallying point for various nationalist movements as Ireland was then part of the United Kingdom of Great Britain and Ireland. Modern historians regard it as a dividing line in the Irish historical narrative, referring to the preceding period of Irish history as "pre-Famine".