Social Darwinism was a belief popularized in the late 19th century that argued that the fittest individuals and societies would survive and thrive, while the weaker ones would be left behind. This belief was used to justify imperialism and colonialism, as countries sought to dominate other countries or regions in order to gain access to resources and expand their power. Countries believed that they were the fittest and that it was their right to dominate other countries or regions in order to spread their own culture and values. This belief also led to the idea of racial superiority, as countries sought to dominate other countries or regions based on the belief that their own race was superior to those of other countries or regions.
