Kiribati consists of about 32 atolls and one solitary island (Banaba), extending into both the eastern and western hemispheres. The groups of islands are:

* Banaba: an isolated island between Nauru and the Gilbert Islands
* Gilbert Islands: 16 atolls located some 930 miles (1,500 km) north of Fiji
* Phoenix Islands: 8 atolls and coral islands located some 1,100 miles (1,800 km) southeast of the Gilberts
* Line Islands: 8 atolls and one reef, located about 2,050 miles (3,300 km) east of the Gilberts

Caroline Atoll channel between west side of Long Island and Nake Island.

Banaba (or Ocean Island) is a raised-coral island which was once a rich source of phosphates, but it was mostly mined out before independence. The rest of the land in Kiribati consists of the sand and reef rock islets of atolls or coral islands which rise but a few metres (half a dozen feet or so) above sea level.

The soil is thin and calcareous, making agriculture very difficult. Kiritimati (Christmas Island) in the Line Islands is the world's largest atoll. Based on a 1995 realignment of the International Date Line, Kiribati is now the easternmost country in the world, and was the first country to enter into the year 2000 at Caroline Island, which, not coincidentally, has been renamed Millennium Island.

According to the South Pacific Regional Environment Program, two small uninhabited Kiribati islets, Tebua Tarawa and Abanuea, disappeared underwater in 1999. The islet of Tepuka Savilivili (Tuvalu; not a Gilbertese name) no longer has any coconut trees due to salination. The United Nations Intergovernmental Panel on Climate Change predicts that sea levels will rise by about half a metre (20 in) by 2100 due to global warming and a further rise would be inevitable. It is thus likely that within a century the nation's arable land will become subject to increased soil salination and will be largely submerged.

However, sea-level rise may not necessarily mean Kiribati will be inundated. Paul Kench at the University of Auckland in New Zealand and Arthur Webb at the South Pacific Applied Geoscience Commission in Fiji released a study in 2010 on the dynamic response of reef islands to sea level rise in the central Pacific. Kiribati was mentioned in the study, and Webb and Kench found that the three major urbanised islands in Kiribati - Betio, Bairiki and Nanikai - increased by 30 per cent (36 hectares), 16.3 per cent (5.8 hectares) and 12.5 per cent (0.8 hectares), respectively.

Kiribati is the only country in the world to be located in both hemispheres and lying on both sides of the 180th meridian.

Kiribati is one of the world's poorest countries. It has few natural resources. Commercially viable phosphate deposits on Banaba were exhausted at the time of independence. Copra and fish now represent the bulk of production and exports. Tourism provides more than one-fifth of GDP. Kiribati is considered one of the least developed countries in the world.

Foreign financial aid, largely from Australia, New Zealand and Japan, is a critical supplement, equal in recent years to 25% to 50% of GDP. Agriculture accounts for 12.4% of GDP and 71% of labour; industry 0.9% of GDP and 1.9% of labour; trade 18.5% of GDP and 4.1% of labour; commercial trade 5.7% of GDP and 1.4% of labour; and service industries 5.7% of GDP and 1.4% of labour. The main trading partners are Australia, USA, France, Japan, Hong Kong and Germany.

In 1956 Kiribati established a sovereign wealth fund to act as a store of wealth for the country's earnings from phosphate mining. In 2008 the Revenue Equalization Reserve Fund was valued at US$ 400 million.

Balance of payments
Kiribati's narrow export base and its enormous need for imports contribute to the country’s large deficit in the merchandise trade balance. However, the country has several sources of external income, including fishing licence fees, investment income, seamen’s remittances and external grants. These inflows are usually more than sufficient to finance the large trade deficit. As a result, Kiribati’s current account balance has been in surplus most of the time in the past decade. International reserves have remained at around US$300 million since 2001.

The native people of Kiribati are called I-Kiribati. The word Kiribati is the local spelling of the word Gilbert and the original name of this British colony was the Gilbert Islands. The indigenous format of the name was adopted when independence was gained in 1979.

Ethnically, the I-Kiribati are Micronesians. Recent archaeological evidence indicates that Austronesians originally settled the islands thousands of years ago. Around the 14th century, Fijians and Tongans invaded the islands, thus complicating the ethnic range; people of Polynesian ancestry further diversified the ethnic typologies. Intermarriage among all ancestral groups, however, has led to a population reasonably homogeneous in appearance and traditions.

The people of Kiribati speak an Oceanic language called "Gilbertese". Although English is the official language, it is not used very often outside the island capital of Tarawa. It is more likely that English is mixed in its use with Gilbertese. Older generations of I-Kiribati tend to use more complicated versions of the language.

Christianity is the major religion, having been introduced by missionaries in the 19th century. The population is predominantly Roman Catholic, although a substantial portion of the population is Congregationalist Protestant. Many other Protestant denominations, including more evangelical types, are also represented. The Bahá'í religion also exists in Kiribati, along with Jehovah's Witnesses and the Church of Jesus Christ of Latter-day Saints (Mormons), the latter numbering 11,511 at the end of 2005.

Human development
The people of Kiribati mostly live in villages with populations between 50 and 3,000 on the outer islands. Most houses are made of materials obtained from coconut and pandanus trees. Frequent droughts hinder reliable large-scale agriculture, so the islanders have largely turned to the sea for livelihood and subsistence. Most are outrigger sailors and fishers. Copra plantations serve as a second source of employment. In recent years, large numbers of citizens have moved to the more urban island capital of Tarawa.

The population of Kiribati has a life expectancy at birth of 60 years (57 for males, and 63 for females) and an infant mortality rate of 54 deaths per 1,000 live births. Tuberculosis is present in the country. Government expenditure on health was at US$268 per capita (PPP) in 2006. In 1990-2007, there were 23 physicians per 100,000 persons. Since the arrival of Cuban doctors, the infant mortality rate has decreased significantly.