The least developed countries (LDCs) are developing countries listed by the United Nations that exhibit the lowest indicators of socioeconomic development. 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) on 18 November 1971.

A country is classified among the Least Developed Countries if it meets three criteria:

• Poverty – adjustable criterion based on Gross national income (GNI) per capita averaged over three years. As of 2018, a country must have GNI per capita less than US$1,025 to be included on the list, and over $1,230 to graduate from it.
• Human resource weakness (based on indicators of nutrition, health, education and adult literacy).
• Economic vulnerability (based on instability of agricultural production, instability of exports of goods and services, economic importance of non-traditional activities, merchandise export concentration, handicap of economic smallness, and the percentage of population displaced by natural disasters).

As of December 2020, 46 countries were still classified as LDC, while six graduated between 1994 and 2020. The World Trade Organization (WTO) recognizes the UN list and says that "Measures taken in the framework of the WTO can help LDCs increase their exports to other WTO members and attract investment. In many developing countries, pro-market reforms have encouraged faster growth, diversification of exports, and more effective participation in the multilateral trading system."