A
reticle, or
reticule , also known as a
graticule , is a net of fine lines or fibers in the eyepiece of a sighting device, such as a telescope, a
telescopic sight, a microscope, or the screen of an oscilloscope. Today, engraved lines or embedded fibers may be replaced by a computer-generated image superimposed on a screen or eyepiece. Both terms may be used to describe any set of lines used for optical measurement, but in modern use
reticle is most commonly used for gunsights and such, while
graticule is more widely used for the covers of
oscilloscopes and similar roles.