¿Qué diferencias hay entre las diferentes categorías de centro poblado: caserío, pueblo, villa, ciudad y metrópoli?

How long did it take you to write all that out? ?

Generally spontaneous human combustion is something that still bewilders some, human combustion happens very rarely and doesn't affect the surrounding areas, so unless you want to set your self on fire, human combustion will remain spontaneous and very rare.

Yes because in graphic design you add elements of art into one piece and/or program. although, you place together graphic designs on a computer,  you still have to know about the principles of design which is included in art.