What is a afterimage?

An afterimage is a type of optical illusion in which an image continues to appear briefly even after exposure to the actual image has ended. There are two major types of afterimages: positive afterimages and negative afterimages. In some instances, the colors of the original stimulus are retained. This is known as a positive afterimage. In other cases, the colors may be reversed. This is known as a negative afterimage.(1)

(1) Verywellmind: Positive and Negative Afterimages