Typology is a system of putting things into groups according to how they are similar. A typology in photography, refers to one or more photographs that have a high level of consistency. This can be in the form of subjects, environments, etc.
Bernd and Hilla Becher are known best for their work with typologies. These consisted of black and white photographs of an industrial structure.
Case study: Bernd and Hilla Becher
The German artists Bernd and Hilla Becher travelled to large mines and steel mills, and systematically photographed the major structures, such as the winding towers that haul coal and iron ore to the surface and the blast furnaces that transform the ore into metal.
A lot of work goes into composing these collections of photographs. It would be very time consuming to find these similar/same structures. However, I imagine it is also quite time consuming to crop and adjust the images in order to create the sense of uniformity and for them to appear identical in order to produce the typology.
By choosing to make the photographs black and white, it maintains the focus on the subject. If there were external factors, (i.e. background settings, contrasting colours, different times of day) then that would make the photos appear different and eliminate the sense of uniformity within the typology.