Once upon a time in a land far, far away, boxing associations and weight divisions were simple. There was only a few sanctioning bodies and 8 weight divisions with one champion per division. It was very clear who was the reigning champion.
Then the 1980's came and everything changed. Sanctioning bodies sprung up all over the place. All it took was a manager or promoter with the fee and their boxer could be fighting for the XYZ world title. Hence, fans and the media started to dub all of these dubious titles a mixture of letters - or alphabet soup.
Today, there are still over 50 sanctioning bodies, however the boxing whos who generally recognize four as the sanctioning bodies each with their own weight divisions. They are:
WBA - World Boxing Association - originated from the National Boxing Association and is the oldest surviving, still active world sanctioning body. 17 weight divisions.
WBC - World Boxing Council - originated around 1963 and is based in Mexico. 17 weight divisions.
IBF - International Boxing Federation - Created in 1983. 17 divisions. It's had a shady history with its founder - Bob Lee being sent to prison for taking bribes and tax evasion. Hit mainstream when Larry Holmes defended the title a number of times.
WBO - World Boxing Organization - Created in 1988. 17 divisions.
As you can see, this results in 17 x 4 = 68 possible champions - 4 possible world champions per weight division depending on which sanctioning body you talk to. It is also the reason you hear the term unified belts or fights billed. To be undisputed world champion, you have to unify the belts - winning them from all 4 sanctioning bodies.
Back to back, the abbreviations of every sanctioning body would be nothing more than a jumbled array of letters - or alphabet soup.