What is the difference between the WBA, WBC, IBF and WBO?

These organisations all recognize each other as legitimate world champion tournament hosts. They originate from different countries, but more often than not have a shared history in one way or another. The IBF for instance started as an offspring from the WBA after an internal power struggle, and the WBO started off after a rules dispute in a WBA meeting. All four are honored by the International Boxing Hall of Fame