Accurate white balance is achieved when a color-less object (like a gray card or pure white paper) has no color cast to it. Generally photographers strive to eliminate the color cast from their images, yet, some light does have a quality of color to it that it will transpose to even a colorless object.
On a sunny day shadows will always have a blue tint (thanks to the blue sky) and a setting sun usually casts a warm golden glow. Your white balance is usually adjusted to counteract just such lighting but what if you went the other way, what if you introduce a color cast in the form of the temperature control either in-camera or through post-processing?
I've shown just such results to show how you can give the illusion that an image was shot in the morning sun, in the moon-light, or when the sun was high in the sky - all by simply adjusting the Temp (yellow and blue control) in Adobe Lightroom.
What is RAW format?
Your camera gives you the option to shoot in RAW or JPG, the advantages of JPG is a much smaller file size which means you can fit more on your card, it takes up less hard drive space, less processing power to edit, takes one less step in your work flow, and overall just goes faster.
So, if speed and efficiency is the name of your game then JPG is the format for you, but what do you trade-off for that speed? The answer is simple, you trade off the ability to make some adjustments later with zero, or much less, loss in quality. RAW files are so much larger because deep within them they contain the ability to pull more detail out of shadows, recover lost detail in highlights, losslessly change the white balance, and much more.
I always shoot RAW, and if you love working in the digital darkroom then you should too!