[rules-users] What is Drools Kie ?

Hi, I need help in KIE API. Need to know that what it is and is there any tutorial available to use Drools KIE. What I have understood googling it out is that it as an API on top of Drools-JBPM, Drools-Guvnor (UberFire), Opta Planner, .. Is kie part of drools-6.x ? And if it is part of drools-6.x then what will be the effect on applications using Drool-5.5 running JBPM5.4, and guvnor 5.5 ? Regards, Zahid Ahmed