Simple Tutorial to Understand Curves in Photoshop & Camera Raw
Curves are by far, the most powerful and versatile color and tone manipulator in Photoshop. Many photographers like Erik Almas & Brooke Shaden swear by it, and is a major part of their workflow. Curves can be very intimidating at first, but once you truly understand how to use them, they will substitute the sliders of Brightness/Contrast, Color Balance, Shadow/Highlights etc. that you are used to.