Happy birthday, Wheel of Fortune!

Forty years ago today, Wheel of Fortune premiered on NBC. The show took a few years to find the winning formula of Pat and Vanna, but the basic elements were there from the beginning -- a big wheel, fabulous prizes and vowels for sale. Here's how the program that TV Guide called the second-best game show of all time (behind Jeopardy!) has changed over the years.

1. Pat Sajak wasn't always the host. When the show premiered, game show icon Chuck Woolery was at the helm.

http://youtu.be/ZIbkfdPcGU0

2. Sajak took over in 1981. Vanna wasn't yet the hostess, though.

http://youtu.be/K7MRhc8va1Q

3. A year later, Vanna debuted. She pretty much looks the same 30+ years later.

http://youtu.be/Yc3-N-8bGPo

4. Pat Sajak left the daytime, network version of Wheel of Fortune in 1989 to host a short-lived talk show. But he made a memorable exit by kissing Vanna White.

http://youtu.be/9TPnoiCmv7w

5. Pat never stopped hosting the syndicated version of Wheel of Fortune. The closest he's come to leaving that was when he walked off the set after contestant made a series of terrible puzzle guesses.

http://youtu.be/dTRCAh2yxug

6. But really, the epic fails are amazing...

http://youtu.be/XeIYtgni5ys

7. ...almost as amazing as the epic wins.

http://youtu.be/p2MEnOvK1H0

WPXI