The Human Development Index (HDI) is a composite index developed by the United Nations Development Programme (UNDP). It measures the average achievements of countries in three dimensions of human development: a long and healthy life, access to education, and a decent standard of living. The HDI is released annually, with the latest report being the 2019 edition.

The number of countries covered in the HDI of 2019 is 189. This means that the HDI covers a vast majority of the world's nations. The report provides a snapshot of the state of human development across the globe and highlights areas where progress has been made and where more work is needed.

The HDI is a valuable tool for policymakers, researchers, and development practitioners as it provides insights into the factors that contribute to human development and helps identify areas where interventions can be most effective. The index also serves as a benchmark against which countries can measure their progress over time.

In conclusion, the HDI of 2019 covers 189 countries and provides a comprehensive picture of human development across the globe. It is an important tool for shaping policies and interventions aimed at improving the lives of people around the world.

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