Alright, so lets start with background.
WCW was a television program broadcasting out of Atlanta. It was not a wrestling league, it was a program broadcast on Saturday nights for the National Wrestling Alliance. Ted Turner bought WCW, he broke with the NWA, turned it into a league of it's own, and launched a bunch of additional television programs.
This is a gross oversimplification.
At the same time, the WWF (now WWE) was gobbling up most of the remaining independent wrestling promotions, until really only WCW and WWF remained.
WCW was southern style wrestling, broadcast out of Atlanta, and steeped in southern wrestling tradition and history.
WWF was ... something else. Shiny, featureless, Regression to the mean.
Both franchises launched a shiny flagship show on Monday Nights kicking off the Monday Night Wars that ran for several years. This was an incredibly competitive and lucrative period in the history of professional wrestling, producing some of the most interesting storylines and matches ever.
Every wrestling fan remembers Nitro and Raw. Everyone remembers the Monday Night Wars.
And everyone who looks into it agrees that the Monday Night Wars ended on Jan 4th 1999 with the finger poke of doom.