Collection Of Computer vision and Image Processing terminology.
Homography is a concept in projective geometry that establishes isomorphism of projective spaces. In simpler terms, it is a bijective relationship between two projective spaces that maps lines to lines or in general conserves the relationship between elements in the different projections.
Any two images of the same planar object, can be compared using homography and projections, assuming the images are taken from a pin-hole camera. The translation and rotation matrices derived between images can help derive camera motion or image similarity.