Blumenbach's final taxonomy of 1795 divided all humans into five groups, defined both by geography and appearance--in his order, the Caucasian variety, for the light-skinned people of Europe and adjacent parts of Asia and Africa; the Mongolian variety, for most other inhabitants of Asia, including China and Japan; the Ethiopian variety, for the dark- skinned people of Africa; the American variety, for most native populations of the New World; and the Malay variety, for the Polynesians and Melanesians of the Pacific and for the aborigines of Australia.
Linnaeus divided the species Homo sapiens into four basic varieties, defined primarily by geography and, interestingly, not in the ranked order favored by most Europeans in the racist tradition--Americanus, Europaeus, Asiaticus, and Afer, or African. In so doing, Linnaeus presented nothing original; he merely mapped humans onto the four geographic regions of conventional cartography.
The overt geometry of Linnaeus's model is not linear or hierarchical. When we visualize his scheme as an essential picture in our mind, we see a map of the world divided into four regions, with the people in each region characterized by a list of different traits.
So a "White" person is according to these taxonomists a person who had come from a region of the northern world.
These taxonomists were "white" themselves.
Any person who considers him or herself as "white", and, who is considered as "white" by a substantial number of other persons who consider themselves as "white", and who generally functions as "white" in all places at all times.
It appears that being "white" is a result of what one has the ability to 'do' in addition to what has done to them.
For example, logically speaking a "White" person has the abilty to practice White supremacy/racsim, while at the same time cannot be subject to that same system of mistreatment on the basis of "Color".
Being "white" seems to have little to do with appearance. Since there are millions of people who are classified as "white" that have darker skin than people classified as 'non-white'.