Ok i know i'm a little late but can someone plzz. tell me what happen between wwe and wcw.?

Well. I've always wondered abt. Wwe and wcw.?? I thought a war started or something. But I'm clueless and I wanna kno every detail. Because this is bugging me. Not knowing what really happened. Like were they combined wwe and wcw.?? What is wcw anyway.?? Was it wwe back then or wwf during wcw times. What really happened someone tell me plzz.