This is a roll bonus system, that is also zero-sum (i.e., points leave the system at about the same rate they enter). "Karma" can be thought of as "favor of the loot gods", where it skews loot towards those with the most favor. You get this favor by attending raids, and lose it when winning items. Specifically the term "DKP" is avoided because karma does not really act as currency. But for those that love the idea of DKP, they can hoard points and then it DOES act as currency... but items can become quite expensive in this case.