Eugenics is a social and scientific movement that emerged in the late 19th and early 20th centuries. It aimed to improve the genetic quality of the human population through selective breeding and other methods. Proponents believed that certain traits, such as intelligence and physical ability, could be enhanced by encouraging reproduction among people with desirable characteristics while discouraging it among those deemed "unfit." The movement gained popularity in various countries, including the United States and Germany, leading to controversial policies such as forced sterilizations and marriage restrictions. Eugenics has since been widely discredited due to its ethical implications and association with human rights abuses, particularly during the Nazi regime.