How ranking for keywords is handled between geographic regions?

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Christine Hansen: The Google regions are split up into different SERPs, so cross SERPs are somewhat unattainable unless the searcher digs deeper or force to search in a specific region outside their own region. We all "stay" inside each of our regions unless we search totally _incognito_. Also since there is a major difference in choice of words, fx "Looking for a flat" (British English) versus "Looking for an apartment" (American English), and "biscuit" vs "cookie", "film" vs "movie", and "holiday" vs "vacation" the mutual intelligibility perishes for a lot more words, than people think. Also, the difference in markets has some bearing on what customers might actually search for. This is why you need to differentiate the textual content based on regions and not language stems. Customers from Britain wouldn`t buy from an American store using American English even if it is within the British region unless it is a super rare item or a super rare price tag - Right off the bat, a British customer would immediately see that the content is for Americans and vice versa.
  
  23h
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  George Mulford: Christine Hansen thanks. Makes a lot more sense now. So would be worth considering creating a .com and .co.uk domains
  
  21h
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  Christine Hansen: George Mulford Definitely!
  
  20h
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  Christine Hansen: George Mulford or /us/... and /uk/...
  
  20h
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  Ash Nallawalla: Keep in mind that there are others like us in the Antipodes who speak and write a kind-of British English, yet we will order online from any outlet that ships here without charging too much.
  
  SERPs can be hyper-local for some products and some in-person services. Google knows that I don`t want a pizza from the next suburb, never mind the next city or country. It knows which products ship internationally, so Amazon dot com ranks well in Australia if there is no Aussie Amazon result for that book.
  
  21h