In order to understand social Darwinism, a few words need to be said about natural Darwinism, i.e., Charles Darwin's theory on survival. In nature, Charles Darwin observed that only the fittest and strongest individuals of any given species managed to overcome the risks of death posed by their search for food, defense against predators and other members of their species. So he came to the conclusion that only the best individuals (from the point of view of a natural selection) were able to survive long enough to produce the next generation, which in turn would tend to improve owing to their parents' traits.
In the late nineteenth century, under the heavy influence of positivism (a philosophical/scientific that rejects anything that cannot be explained or described by mathematics or science, God, for example), Darwinism was twisted and applied to the field of sociology, as a convenient way to justify slavery, social inequality, poverty, segregation and racism. Social Darwinism argued, fo example, Africans were subpar individuals, as compared to Caucasians, and that explained why they had been enslaved in past centuries and were, at the turn of the twentieth century, under European rule.
Today social Darwinism is mostly applied to individuals of any race or social condition who fail to develop a sound degree of common sense. Cases of people getting killed while walking and taking selfies on the street because they get run over by cars or fall into open sewers can be seen today as cases of social Darwinism since the people involved in these fatal accidents could have easily prevented them by not distracting their attention while walking down the street.
