Have you ever seen a photo that just made you say "Wow"? That simply stood out from all of the other photos you've seen lately and you just knew, that the photographer was a professional? Chances are it's the post processing (editing) that made it look so good.
Post processing isn't about "Photoshopping the perfect picture" but rather, taking your photo and turning it into the best quality and most visually compelling image that it can be.
Cameras are only so good at capturing and displaying the true beauty of a scene, but they are far from perfect! When your camera fails to bring out the color and details that you want presented, it's up to the photographer to bring the image back to life, using post processing. See the Before and After examples below...