Long time ever since the end of WW2, the rich countries on planet have devised a standard to distinguish other poor countries on the planet.
They title themselves as the first world countries, the “developed” countries. To hit the standard of developed countries, according to Wikipedia,
Economic criteria have tended to dominate discussions. One such criterion is income per capita; countries with high gross domestic product (GDP) per capita would thus be described as developed countries. Another economic criterion is industrialization; countries in which the tertiary and quaternary sectors of industry dominate would thus be described as developed. More recently another measure, the Human Development Index (HDI), which combines an economic measure, national income, with other measures, indices for life expectancy and education has become prominent. This criterion would define developed countries as those with a very high (HDI) rating.