You've set the best shooting-mode for the occasion; you've got the right f-stop for the subject; you see the light-meter showing a correct exposure - you click.
Perfect shot, right?
Not necessarily.
The technology you hold in your hand, when working with your DSLR, is nothing short of magic : shutter opening-closing in a micro-second; photons impinging on sensor; millions of pixels firing - image appearing on-screen!
Miraculous as this may be, it still cannot match the magnificence of The Ultimate Seeing Machine - The Human Eye.
There is no machine out there that can compete with how clearly, accurately, and quickly, the eye renders light, color, and texture. Our eyes see and show us things exactly as they are.
Which is why you always want to process your photos.
Starting with your great shot, bumping up the contrast-levels gets you clearer outlines, adjusting color-saturation gives you a richer palette, and increasing brightness brings in that bit of sun, that you saw, but your camera didn't.
And before you know it, you're holding the moment - just the way you happened to have seen it!
Happy Photographing!!