https://phlearn.com/tutorial/color-tone-using-gradient-maps/
Imagine a gradient. What comes to mind? We’re willing to bet that you’re picturing one color gradually fading into another. While simple color transitions are great for backgrounds and birthday cards, gradients in Photoshop can do so much more.

 

 

Learn how to use the power of gradients for blending layers and adjustments, professional color toning, and for creating photo-realistic effects like lens flares and light leaks. This tutorial also includes 35 custom Photoshop gradients that you can use right away to add amazing effects to your photos!