The Least Developed Countries (LDCs) is a list of the countries that, 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. The concept of LDCs originated in the late 1960s and the first group of LDCs was listed by the UN in its resolution 2768 (XXVI) of 18 November 1971. A country is classified among the Least Developed Countries if it meets three criteria:
LDC criteria are reviewed every three years by the Committee for Development Policy (CDP) of the UN Economic and Social Council (ECOSOC). 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 (UN-OHRLLS) coordinates UN support and provides advocacy services for Least Developed Countries. The classification (as of June 2017) applies to 47 countries.
Since the LDC category was initiated, only four countries have graduated to developing country status. The first country to graduate from LDC status was Botswana in 1994. The second country was Cape Verde in 2007. Maldives graduated to developing country status on 1 January 2011, while Samoa graduated in 2014. It is anticipated that Equatorial Guinea and Vanuatu will be the next countries to be promoted from LDC status, followed by Angola. At the UN's fourth conference on LDCs, which was held in May 2011, delegates endorsed a goal targeting the promotion of at least half the current LDC countries within the next ten years.
There are three countries which presently meet the criteria for LDC status, but have declined to be included in the index, questioning the validity or accuracy of the CDP's data: Ghana, Papua New Guinea, and Zimbabwe.
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 Although many contemporary scholars argue that "Third World" is outdated, irrelevant or inaccurate, others may use the term "Fourth World" in reference to least developed countries (although Fourth World is also used to refer to stateless ethnic groups). The term "less economically developed country" (LEDC) is also used today.
However, in order to avoid confusion between "least developed country" and or LEDC "less economically 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".
During a United Nations review in 2009, 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 $905. Countries with populations over 75 million are excluded.
There have been four United Nations conferences on LDCs, held every ten years. The first two were in Paris, in 1981 and 1991; the third was in Brussels in 2001.
The Fourth UN Conference on Least Developed Countries (LDC-IV) was held in Istanbul, Turkey, 9–13 May 2011. It was attended by Ban Ki-Moon, the head of the UN, and close to 50 prime ministers and heads of state. The conference endorsed the goal of raising half the existing Least developed countries out of the LDC category by 2022. As with the Seoul Development Consensus drawn up in 2010, there was a strong emphasis on boosting productive capability and physical infrastructure, with several NGOs not pleased with the emphases placed on the private sector. 
In the process of increasing awareness towards the needs of the LDCs, the importance of the inputs and contributions of the members of the Civil Society were first acknowledged during the NGO Forum held in parallel to the third UN Conference on Least Developed Countries in Brussels in 2001. The importance of civil society and its contributions has also been recognised in the UNGA Resolution 63/227. Post LDC III, civil society actors have been actively engaged and involved in the UN Decision making processes concerning LDCs. They have also been involved in the implementation and follow-up, monitoring and review of the progress made by LDCs and the success of the implementation of the BPoA. For LDC IV, the UN-OHRLLS has entrusted LDC Watch, a global network of LDC Civil Society Organizations (CSOs), with taking the lead in coordinating the civil society track.
LDC Watch has organised civil society consultations at various levels. At the regional level, in partnership with the UN-OHRLLS and relevant UN agencies, the following three consultations have been organised:
These consultations were organised to critically assess the progress made by LDCs in the ten years since the adoption of the Brussels Programme of Action and with the intention of influencing the outcome of LDC IV.
As the LDC Governments and their development partners prepare to gather together for UNLDC IV, members of Civil Society are also preparing to meet during the Civil Society Forum,  which is going to be held in parallel to the official conference. UN-OHRLLS has mandated LDC Watch as the lead Civil Society Organization to coordinate the Civil Society track towards the LDC-IV conference. The Forum will open two days before the official conference begins and will continue till the end of the conference. It will bring together NGOs from all the LDCs, as well as representatives from the civil society at all levels including women’s movements, youth movements, trade unions, peasant federations, media personnel and human rights defenders.
Issues surrounding global trade regulations and LDCs have gained a lot of media and policy attention thanks to the recently collapsed Doha Round of World Trade Organization (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.
Dr. Chiedu Osakwe, as of 2001 the Director, Technical Cooperation Division at the Secretariat of the WTO, and adviser to the Director-General on developing country matters, was appointed as the WTO Special Coordinator for the Least Developed Countries beginning in 1999. He worked closely with the five other agencies that together with the WTO constitute the Integrated Framework of action for the Least Developed Countries. They addressed issues of market access, special and differential treatment provisions for developing countries, participation of developing countries in the multilateral trading system, and development questions, especially the interests of developing countries in competition policy. At the 28th G8 summit in Kananaskis, Alberta, Canadian Prime Minister Jean Chretien proposed and carried the Market Access Initiative, so that the then 48 LDCs could profit from "trade-not-aid".