Spherical images are a type of image projection which appear perspectively correct when 'wrapped' around a sphere. This 'wrapping' is usually done with a computer, to view a 360 degree image as a Virtual Reality image.
These images cover a field of view of 360 by 180 degrees. Some salespeople (such as IPIX) try to tell you that their images are 360 by 360 degrees. This is fact wrong. 360 x 180 degrees allows a complete view of a scene, horizontally and vertically.