The term "point spread function" refers to the mathematical model used to describe how a point source of light appears in an image. Synonyms for this term include "PSF" or "image blurring function". Other terms such as "optical transfer function", "rayleigh criterion" or "image resolution" may also be associated with the point spread function. Understanding the point spread function is essential for image processing and optical system design. It is used to analyze the degree of blurring in an image caused by factors such as lens defects, atmospheric turbulence or sensor limitations. In essence, the point spread function is a critical component of understanding the behavior of optical systems and image formation.