Most People are used to using the sliders when working with Lightroom and whilst that is fine, you sometimes never really explore the full potentials of your images and that is where tone curves come in.
Using the curves adjustments available in Lightroom (and laws taught can be applied on Photoshop as well), you open yourself and your images to more than just brightening shadows and reducing highlights. In the Video below, Nigel Danson delves deeply into the use of curve tones and all the ways they can affect your image’s brightness, contrast and even affect individual colors hence expanding the ways with which you could color-grade your images.