Originally posted by toeternitoe
Note, though, that this only describes the current system. Previously, FIDE has awarded grandmaster titles because, well, sometimes because the officials of the day felt like it, sometimes for political reasons, and sometimes because it was actually deserved. And before FIDE was the one source of "official" titles, anyone who had won an international tournament was sometimes called a Grand Master.
The result of all this is that some people who have held the grandmaster title would never get it today, while some who have one now would not have had it before 1950. And in all of those cases, you'll find some for whom this is now, or was then (or both! ), seen as justified, and some unjustified. Basically, there does not seem to be a perfect system for awarding master titles, or even a better than adequate one.