How was social darwinism used as a justification or explanation for imperialism?

Social Darwinism held that those made better or worse by industrialization were based on the natural predisposition of the people effected. For those who were made better off, the success of those people demonstrated that they had a well-evolved culture and this expansion would help remove or improve underperforming cultures, which were those "chosen" by the fact that they were performing poorly.

All in all, according to the Social Darwinist, Imperialism was the natural expansion and success of a well-evolved culture and this expansion would help remove or improve underperforming cultures.