The WBC, WBA, WBO and IBF are the official belts recognized by the International Boxing Hall of Fame. The WBA was the fist of these organizations and the WBC was the second.
Each of these "sanctioning bodies" has it's own top 10 rankings and its own champion at each weight class. Of course, some fighters hold several of the belts and some only have one.
In order for each fighter to keep his belt he must pay a fee to that sanctioning body before every fight. And oft times the sanctioning bodies will give him a '"mandatory fight" that he must fight in order to keep his title. Most of the time this "mandatory" fight is against an undeserving opponent, someone whose manager may have worked out a "deal" to get the fight.
This means in some cases the Champion will fight a number 10 ranked guy when the number 4 ranked guy still has not had a shot at the title.
So, the WBC may say their champ Orc is to fight Pizowell on this day. If Orc also has the IBF belt they may say to Orc, "Sorry but you must fight Stingray next or lose your belt, so your fight with Pizowell must be postponed.
Then Orc has to decide which belt to keep and which to vacate. Orc could also pay a huge fine to one of the sanctioning bodies and keep both. Every organization is out to make money.
So which belt has the most prestige and which champion is the true champion? Most people trace the champion back by who beat who more than the belt they carry.
Is it me or is that ridiculously difficult to understand?