Background gradient of poster image

Quick answer：

A background gradient in poster design refers to a visual technique where the colors transition smoothly from one to another across the background. This is often used to create depth, draw attention, or establish a mood. In digital design, gradients can be created using various software tools like Adobe Photoshop, Illustrator, or graphic design platforms. They come in different types, such as linear, radial, angle, and diamond gradients, each with its own characteristics and applications.