We have already discussed that shaders process either vertices or pixels. So, the basic working principle is to change or manipulate data at runtime:

A shader process is a specific set of instructions to process vertices or fragments. Different shader programs can be written for various types of processing.

A vertex shader is used to change the shape of the model; it can also change the surface-formation system.

Pixel/fragment shaders can change the pixel color value along with opacity. Pixel data can be merged, modified, or replaced by a shader program to form a new digital image.