BDO - British Darts Organisation
PDC - Professional Darts Corporation
BDO was the original governing body, the PDC was formed in '93 because the players wanted to make more money and thought the BDO were useless (Darts was huge on telly in the 80s, but all the sponsors and TV coverage disappeared by the end of the decade).
The top 16 players quit the BDO, signed a deal with Sky Tv and had their own World Championship in '94, it started off smaller but now is huge - only Football gets better ratings on Sky Sports and their final gets 8x the attendance (read more here http://en.m.wikipedia.org/wiki/Split_in_darts
The ironic thing is that the guy who used to run the BDO and who arguably is the reason for the split lives only a mile from where the PDC hold their World Championship.........