The selection is random and is done by a computer at the U.S. Department of State. 55,000 Green Cards are issued globally each year.
Selected vs Not Selected
You have been selected
"You have been randomly selected for further processing in the Diversity Immigrant Visa Program".
You have NOT been selected
"Based on the information provided, the Entry HAS NOT BEEN SELECTED for further processing for the Electronic Diversity Visa program at this time."