Thanks a lot, pandas!
Back in 1961, a group of animal lovers got together and formed the World Wildlife Fund and called it WWF for short. In 1979, the World Wide Wrestling Federation dropped the Wide from its name and also started going by the WWF abbreviation.
And because people are so dumb and will confuse musclebound jocks in speedos with koala conservationists, the two companies had to reach an agreement to ensure proper use of the initials.
From Wikipedia:
In 2000, the World Wide Fund for Nature (also trademarked WWF), an environmental organization, sued World Wrestling Federation Entertainment Inc. in the United Kingdom. The Law Lords agreed that the promotion company had violated a 1994 agreement as Titan Sports which had limited the permissible use of the WWF trademark in Europe, particularly in merchandising.
The first thing that sticks out is the fact that the UK has Law Lords. That's so dope. It's so much cooler than just being a dumb, ol' judge, right? The second thing I notice is Americans didn't do anything wrong but yet again, those pesky Europeans are messing it up for everyone else!
So Vince McMahon had to change his company's name and simply swapped out "federation" for "entertainment" and voila -- WWE.
May 5, 2002, WWE.com went live and and the company changed all WWF references to the new initials. The following evening on Raw featured a fancy commercial ushering in the "E Era".
Check it out after the jump.