Carte-de-visite
From George Eastman House : Notes On Photographs
The carte-de-visite--a paper photograph mounted on card stock measuring approximately 4 x 2½ inches--was the most popular format for portrait photography in the nineteenth century. A carte-de-visite was roughly the same size as the visiting cards that gave the format its name. Cartes-de-visite were often exchanged between friends and family members and were collected in specially made albums. The format became popular in the late 1850s when a technique was developed for making multiple negatives on a single glass plate (thereby reducing the cost of portrait photography), and it remained popular through the 1860s. The larger cabinet card format gradually eclipsed the popularity of the carte-de-visite.