A more thorough explanation:

The diversity visa program (the lottery) is a program run by the U.S. Department of State that randomly selects around 50,000 people each year to apply for a U.S. visa. To enter the lottery, individuals must meet certain educational and other requirements. Those who are selected are subject to security checks. Visas are allocated based on global region, with no more than 7% of total visas allotted to each individual region. The number of visas given to each country within a region is based on previous immigration trends, with countries that have had lower levels of immigration to the United States in the past five years receiving more visas.

Every year, the U.S. Department of State runs the diversity visa program, also known as the lottery. This program randomly selects individuals from around the world to apply for a U.S. visa. For example, if someone from Ghana meets the educational and other requirements, they can enter the lottery. If they are selected, they can apply for a U.S. visa. However, not everyone who enters the lottery is guaranteed a visa. The number of visas given to each country is based on previous immigration trends. For example, if fewer people from Ghana have immigrated to the United States in the past five years, then more visas may be given to Ghanaians in the current year's lottery.

This program is designed to promote diversity in the United States by allowing people from countries with historically low levels of immigration to have a chance to come to the United States. It also helps to ensure that visas are distributed fairly across different regions of the world.