Three color gradient reference

Quick answer：

A color gradient is a smooth transition between two or more colors. In the context of design and graphics, three-color gradients are often used to create visually appealing backgrounds, transitions, or effects. They can be created using various software tools such as Adobe Photoshop, Illustrator, or GIMP. The process typically involves selecting three colors and adjusting their blend mode and opacity to create a seamless transition between them.