Given the proliferation of pictures of people in circulation today, it is no surprise that portraiture and self-portraiture have been among the most common forms of photography throughout the medium’s history. In the mid-nineteenth century people collected and exchanged cartes de visite, small images mounted on board, as calling cards. This is an example of an uncut sheet of images by Disdéri, who patented cartes de visite and the method of making eight negatives on a single plate, showing the subject in a variety of poses
Additional text from Seeing Through Photographs online course, Coursera, 2016