Short answers, pulled from the story.
The World Bank classifies economies into four groups based on gross national income per capita. For the 2022 fiscal year, a low-income country had a GNI per capita below 1,045 US dollars; lower-middle income fell between 1,046 and 4,095 dollars; upper-middle income between 4,096 and 12,695 dollars. Countries in the three non-high-income groups are together called low and middle-income countries (LMICs).
In 2015, the World Bank declared the developing-versus-developed categorization had become less relevant due to worldwide improvements in child mortality rates, fertility rates, and extreme poverty rates. In its 2016 World Development Indicators, it stopped distinguishing between developed and developing countries, replacing that division with data aggregated by region and income group.
Current estimates indicate that nearly two-thirds of people living in extreme poverty are in Sub-Saharan African countries.
The World Health Organization estimated in 2015 that 663 million people lacked access to safe and clean drinking water, while 2.4 billion people lacked adequate sanitation facilities.
Brunei, Hong Kong, Kuwait, Macao, Qatar, Singapore, and the United Arab Emirates have been cited and criticized for claiming developing-country status at the World Trade Organization. This status entitles them to preferential treatment despite meeting developed-economy benchmarks by nearly every economic metric.
Economies in the least-developed countries lost an average of 7 percent of their gross domestic product in 2010, mainly due to reduced labor productivity from climate-related impacts. Rising sea levels alone cost 1 percent of GDP to the least-developed countries that year, and 4 percent in the Pacific.