Hey Photoshop users! Are you using Curves adjustments? You should be. Otherwise, you’re missing out on one of Photoshop’s most powerful tools. The idea of the Curves tool is this: when you create a Curves adjustment layer, you are presented with a line graph over a histogram representing the tones in your image. You can click the line to create points and drag tones up or down corresponding to where the point sits on the histogram.
To make the most of the Curves tool, you need to understand how to read a histogram. If you aren’t quite sure, you can brush up on that skill here.
Curves can be a bit mystifying at first, but with a little prerequisite knowledge and a guided walkthrough like this one provided by Nathaniel Dodson of tutvid, you can jump in and utilize the tool. 
An Easy Curves Trick
One of the first things many people learn to do with Curves is to create the beloved “s-curve.” You’ve probably heard it mentioned before, and that’s because it’s a quick, foolproof way to add highly controllable contrast to your photos in Photoshop (or any program that uses Curves.)
What’s an “s-curve?” It is literally an “s” shape in the line that spans from the lower left corner (the black point) and the upper right corner (the white point.) There is a grid across the histogram, and using this grid, you can click the Curves line in the middle of the left and right halves of the graph.
By dragging the left point that you’ve created down to lower the brightness of the mid-blacks and the right point up to raise the mid-whites, you increase contrast. The amount you choose to drag determines the results, and you can also control the look with the layer’s opacity slider.
[Rewind:] Photoshop Tips | Photoshop ‘Auto Adjustments’ For One-Click Color Correction
S-curves are just the very tip of the iceberg, though. Check out Nathaniel’s video below to dive deeper and learn about making targeted adjustments, using the individual channels, and find explanations for those oddities you may have created by accident using the Curves tool, and how to avoid doing it again.
