A more thorough explanation:

An underdeveloped country is a country that is not as economically or politically advanced as the main industrial powers. These countries are mostly located in Africa, Asia, Eastern Europe, the Middle East, and Latin and South America. They are also known as developing countries, developing states, less-developed countries, or Third World countries.

The term "underdeveloped countries" was first used in the late 1940s in economic literature and international organizations. It was later replaced by "less developed countries" in the 1950s, and eventually "developing countries." These terms all refer to the same group of countries.

Examples of underdeveloped countries include Afghanistan, Haiti, and Yemen. These countries have lower levels of economic development and political stability compared to industrialized countries like the United States, Japan, and Germany. They often struggle with poverty, lack of infrastructure, and limited access to education and healthcare.

These examples illustrate the definition of underdeveloped countries by showing how these countries are not as economically or politically advanced as industrialized countries. They also highlight the challenges that underdeveloped countries face in terms of poverty and lack of resources.