Invisibilityis the state of an object that cannot be seen. An object in this state is said to beinvisible(literally, "not visible"). The term is often used in fantasy/ science fiction, where objects are literally made unseeable by magicalor technologicalmeans; however, its effects can also be demonstrated in the real world, particularly in physicsand perceptual psychologyclasses. Since objects can be seen by light in the visible spectrumfrom a source reflecting off their surfaces and hitting the viewer's eye, the most natural form of invisibility (whether real or fictional) is an object that neither reflects nor absorbs light (that is, it allows light to pass through it). This is known as transparency, and is seen in many naturally occurring materials (although no naturally occurring material is 100% transparent). Visibility also depends on the eyesof the observer and/or the instruments used. Thus an object can be classified as "invisible to" a person, animal, instrument, etc. In research on sensorial perceptionit has been shown that invisibility is perceived in cycles. [ 1 ] Invisibility is often considered to be the supreme form of camouflage, as it does not reveal to the viewer any kind of vital signs, visualeffects, or any frequencies of the electromagnetic spectrumdetectable to the human eye, instead making use of radio, infraredor ultravioletwavelengths.