Ireland is the third largest island in Europe and the twentieth largest in the world. It lies to the northwest of Continental Europe. It 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 Republic of Ireland (also known simply as Ireland) covers five sixths of the island, with Northern Ireland, part of the United Kingdom, covering the remainder in the northeast. The name 'Ireland' derives from Old Irish Ériu (in modern Irish, Éire) with the addition of the Germanic word 'land'. This word, from Proto-Celtic, which also gave Middle Welsh "Irish Sea", originally meant "fatness", in the sense of fertile.

The population of the island is slightly under six million (2006/7), with almost 4.25 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.

A ring of coastal mountains surrounds low central plains. The highest peak is Carrauntoohill (Irish: Corrán Tuathail) in County Kerry, which is 1,041 m (3,414 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.

In the 1920s and early 1930s, the Republic of Ireland pursued a low-tax, low-spending policy under the government of W. T. Cosgrave and Cumann, focused mainly on agriculture, livestock farming being of primary importance. The only notable expense the government went to during this time was for the rural electrification scheme, which saw £5,000,000 being spent constructing the Ardnacrusha hydroelectric power station on the river Shannon. During this period, 97% of trade was done with Britain.

Construction plays an important role in the Irish economy in 1932, Eamonn De Valera's Fianna Fáil party defeated Cosgrave's party with a solid majority. De Valera focused on agriculture again. Fianna Fáil abandoned free trade and put up protective tariffs on almost all industries, spurring a long economic war with the United Kingdom, who taxed imports from Ireland in retaliation. The economic war resulted in widespread hardship for Irish farming. It ended in 1938, when control of several naval ports in the country was transferred to the Free State. Fianna Fáil remained in power until 1948, when the first coalition government ousted them from power. To the present day, the two largest parties, Fianna Fáil and Fine Gael, have dominated the scene, Fine Gael traditionally being pro-business, low tax and low spending, although with Fianna Fáil's alliance with the Progressive Democrats, it has modified its standpoint to be more pro-business.

Northern Ireland experienced a boom during World War II and received British support thereafter. In comparison, the Republic did not experience a WWII boom and its situation declined relative to Northern Ireland. Overall, until the early 1960s, population and economic decline plagued Ireland. In the early 1960s, Seán Lemass became Taoiseach and embarked on a program of economic reform. For the first time in Ireland, second level education was made free and compulsory. The Republic abandoned protectionism and applied to join the European Economic Community, along with Britain, gaining entry in 1973.