According to Kipling, what was the "white man's burden"?

The poem exhorts the reader to take up the white man’s burden by sending the best of their country to dark, uncivilized places of the earth. There they should try to end famine and disease and serve their new captives - the native peoples. The poem smacks of cultural imperialism, with the superior English going into a country of “sullen” brutes and imposing their civilizing behaviors and institutions.