World map (updated 2019) showing advanced, transitioning, less and least developed countries. The CIA gives the following definitions:

• Advanced Economies: A term used by the International Monetary Fund (IMF) for the top group in its hierarchy. Similar to the term "Developed countries" but adds Hong Kong, South Korea, Singapore and Taiwan, but drops Malta, Mexico, South Africa, and Turkey.
• In transition: A term used by the International Monetary Fund (IMF) for the middle group in its hierarchy. This group is identical to the group traditionally referred to as the "former USSR/Eastern Europe". The group includes the countries which are close to reaching "advanced economy" status, such as Moldova, Albania, Montenegro, North Macedonia, Serbia, Bosnia and Herzegovina, Armenia, Georgia, Azerbaijan, Turkmenistan, Uzbekistan, Kazakhstan, Kyrgyzstan, Tajikistan, Belarus, Ukraine, and China
• Less developed: The bottom group in the hierarchy. Mainly countries and dependent areas with low levels of output, living standards, and technology; per capita GDPs are generally below $5,000 and often less than $1,500; however, the group also includes a number of countries with high per capita incomes, areas of advanced technology, and rapid rates of growth; includes the advanced developing countries, developing countries, low-income countries, middle-income countries, newly industrialized economies (NIEs), the South, Third World, and underdeveloped countries. Includes OECD and G-20 Industrial Nations members like Brazil, Mexico and Turkey, because the Russian editor who prepared this map misinterpreted the definition made by the IMF.
• Least developed: Subgroup of the less developed countries (LDCs) initially identified by the UN General Assembly in 1971 as having no significant economic growth, per capita GDPs normally less than $1,000, and low literacy rates; also known as the undeveloped countries.

Note: Due to overlap I removed the "four tigers" and the "least developed" countries from the "less developed" list and added Mongolia.