3D photographs are images that create the illusion of depth, allowing viewers to perceive a three-dimensional effect. This is typically achieved through techniques like stereoscopy, where two slightly different images are presented to each eye, mimicking how human vision works. These photographs can be viewed using special glasses or devices, such as 3D viewers or virtual reality headsets. They are commonly used in various fields, including cinema, video games, and medical imaging, enhancing the visual experience by making scenes appear more lifelike and immersive.