I came across a quite impressive list of boxing organizations (link to a French Wikipedia page without its English version). Why do so many organizations exist? WBA, WBO, WBC, IBF, IBC, IBO, etc.
(Choose a 3 or 4 letter acronym having a B and you have a good chance of finding one of their names).
It seems they all run in parallel, with their own title holders, but we can also see boxers being able to get belts from different organizations, like for example Jermain Taylor unifying (think it's the right term) the WBA, WBC, WBO and IBF titles.
So, how are all those organizations related? Does a boxer have to choose an organization in the list before fighting? How does all of this work?