Ireland is the third largest island in Europe, and the twentieth-largest island in the world. It lies to the north-west of continental Europe and is surrounded by hundreds of islands and islets. To the east of Ireland, separated by the Irish Sea, is the island of Great Britain. Politically, the state Ireland (described as the Republic of Ireland in cases of ambiguity) covers five-sixths of the island, with Northern Ireland, part of the United Kingdom, covering the remainder in the north-east.
The population of the island is slightly over six million (2007), with 4.34 million in the Republic of Ireland (1.7 million in Greater Dublin) and an estimated 1.75 million in Northern Ireland (0.6 million in Greater Belfast). This is a significant increase from a modern historical low in the 1960s, but still much lower than the peak population of over 8 million in the early 19th century, prior to the Irish potato famine.
The name Ireland derives from the name Ériu (in modern Irish, Éire) with the addition of the Germanic word land. Most other western European names for Ireland derive from the same source, such as French Irlande, Spanish, Italian and Portuguese Irlanda, German Irland and Dutch Ierland. A ring of coastal mountains surrounds low central plains. The highest peak is Carrauntoohil (Irish: Corrán Tuathail) in County Kerry, which is 1,038 m (3,406 ft). The River Shannon, at 386 km (240 miles) is the longest river in Ireland. The island's lush vegetation, a product of its mild climate and frequent but soft rainfall, earns it the sobriquet "Emerald Isle". The island's area is 84,412 km² (32,591 square miles).
Ireland's least arable land lies in the south-western and western counties. These areas are largely mountainous and rocky, with dramatic green vistas, hence the attributive name "the Emerald Isle".
Climate
Overall, Ireland has a mild, but changeable, Oceanic climate with few extremes. The warmest recorded air temperature was 33.3 °C (91.94 °F) at Kilkenny Castle, County Kilkenny on 26 June 1887, where as the lowest recorded temperature was ?19.1 °C (?2.38 °F) at Markree Castle, County Sligo on 16 January 1881.
Other statistics show that the greatest recorded annual rainfall was 3,964.9 mm (156.1 in) in the Ballaghbeena Gap in 1960. The driest year on record was 1887, with only 356.6 mm (14.0 in) of rain recorded at Glasnevin, while the longest period of absolute drought was in Limerick where there was no recorded rainfall over 38 days during April and May of 1938.
The climate is typically insular, and as a result of the moderating moist winds which ordinarily prevail from the South-Western Atlantic, it is temperate, avoiding the extremes in temperature of many other areas in the world at similar latitudes.
Precipitation falls throughout the year, but is light overall, particularly in the east. The west, however, tends to be wetter on average and prone to the full force of Atlantic storms, more especially in the late autumn and winter months, which occasionally bring destructive winds and high rainfall totals to these areas, as well as snow and hail. The regions of North Galway and East Mayo have the highest incidents of recorded lightning annually (5 to 10 days per year). Munster in the south records the least snow with Ulster in the north more prone to snow. Some areas along the south and southwest coasts have not had any lying snow since February 1991.
Inland areas are warmer in summer, and colder in winter - there are usually around 40 days of below freezing temperatures (0 °C/32 °F) at inland weather stations, but only 10 days at coastal stations. Ireland is sometimes affected by heat waves, most recently 1995, 2003, 2006.
Geology
Geologically the island consists of a number of provinces - in the far west around Galway and Donegal is a medium to high grade metamorphic and igneous complex of Caledonide (Scottish Highland) affinity. Across southeast Ulster and extending southwest to Longford and south to Navan is a province of Ordovician and Silurian rocks with more affinities with the Southern Uplands province of Scotland. Further south, there is an area along the Wexford coast of granite intrusives into more Ordovician and Silurian rocks with a more Welsh affinity.
In the southwest, around Bantry Bay and the mountains of Macgillicuddy's Reeks, is an area of substantially deformed but only lightly metamorphosed Devonian-aged rocks.
This partial ring of "hard rock" geology is covered by a blanket of Carboniferous limestone over the center of the country, giving rise to the comparatively fertile and famously "lush" landscape of the country. The west coast district of The Burren around Lisdoonvarna has well developed karst features. Elsewhere, significant stratiform lead-zinc mineralization is found in the limestones (around Silver mines and Tynagh).
Hydrocarbon exploration is continuing. The first major find was the Kinsale Head gas field off Cork/Cobh by Marathon Oil in the mid-1970s. More recently, in 1999, Enterprise Oil announced the discovery of the Corrib Gas Field. This has increased activity off the west coast in parallel with the "West of Shetland" step-out development from the North Sea hydrocarbon province. Exploration continues, with a frontier well planned north of Donegal for August 2006 and continuing drilling of prospects in the Irish Sea and St Georges Channel. | 
