Least Developed Countries (LDCs or Fourth World countries) are countries which according to the United Nations exhibit the lowest indicators of socioeconomic development, with the lowest Human Development Index ratings of all countries in the world. A country is classified as a Least Developed Country if it meets three criteria  based on:
- low-income (three-year average GNI per capita of less than US $750, which must exceed $900 to leave the list)
- human resource weakness (based on indicators of nutrition, health, education and adult literacy) and
- economic vulnerability (based on instability of agricultural production, instability of exports of goods and services, economic importance of non-traditional activities, merchandise export concentration, and handicap of economic smallness, and the percentage of population displaced by natural disasters)
Countries may "graduate" out of the LDC classification when indicators exceed these criteria. The United Nations Office of the High Representative for the Least Developed Countries, Landlocked Developing Countries and Small Island Developing States coordinates UN support and provides advocacy services for Least Developed Countries.
The classification currently applies to around 49 countries (as of June 14, 2007).
In 2007, the United Nations graduated Cape Verde from the category of Least Developed Countries. This is only the second time it has happened to a country. The first country to graduate from LDC status was Botswana in 1994. Samoa may become the third country to graduate in this manner , with a decision on this issue scheduled for 2008.
Usage and abbreviations
Least developed countries can be distinguished from developing countries, "less developed countries", "lesser developed countries", or other terms for countries in the so-called "Third World". Although many contemporary scholars argue that "Third World" is outdated, irrelevant or inaccurate, others may use the term "Fourth World" in reference to least developed countries.
However, in order to avoid confusion between "least developed country" and "less developed country", which may both be abbreviated as LDC, and to avoid confusion with landlocked developing country, which can be abbreviated as LLDC, "developing country" is generally used in preference to "less developed country".
Least developed countries generally suffer conditions of extreme poverty, ongoing and widespread conflict (including civil war or ethnic clashes), extensive political corruption, and lack political and social stability. The form of government in such countries is often authoritarian in nature, and may comprise a dictatorship, warlordism, or a kleptocracy. AIDS is a major issue in a lot of these countries. The majority of LDCs are in Sub-Saharan Africa.
Note, however, that the above characteristics generally do not apply to LDCs located in Oceania. Kiribati, Samoa, Tuvalu and Vanuatu are politically stable democracies, and lack any form of civil or ethnic strife. Nor are they strongly affected by AIDS. Although they have small economies, often dependent on monocultures, the population generally does not suffer from extreme poverty, thanks to an enduring subsistence sector in the economy. The Solomon Islands is the only Oceanian LDC currently affected by political instability and ethnic tension. In 2006, the United Nations recommended that Samoa be upgraded from LDC status to that of Developing Country. The Samoan government disagreed, and asked for a review of the recommendation.  Samoa retains LDC status, pending a decision scheduled for 2008.
During the last United Nations review in 2003, the UN defined LDCs as countries meeting three criteria, one of which was a three-year average estimate of gross national income (GNI) per capita of less than US $750. Countries with populations over 75 million are excluded. 
Trade and LDCs
Issues surrounding global trade regulations and LDCs have gained a lot of media and policy attention thanks to the recently collapsed Doha Round of WTO negotiations being termed a development round. During the WTO's Hong Kong Ministerial, it was agreed that LDCs could see 100 percent duty-free, quota-free access to U.S. markets if the round were completed. But analysis of the deal by NGOs found that the text of the proposed LDC deal had substantial loopholes that might make the offer less than the full 100 percent access, and could even erase some current duty-free access of LDCs to rich country markets.  , Dissatisfaction with these loopholes led some economists to call for a reworking of the Hong Kong deal. 
Adapted from the Wikipedia article, "Least Developed Countries" http://en.wikipedia.org/wiki/Least_Developed_Countries, used under the GNU Free Documentation License.
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