title: Daguerreotype
context: Invented by Louis-Jacques-Mandé Daguerre and introduced worldwide in 1839,[4][5][6] daguerreotype was almost completely superseded by 1860 with new, less expensive processes yielding more readily viewable images. In the late 20th century, there was a revival of daguerreotypy by a small number of photographers interested in making artistic use of early photographic processes.
question: When was the daguerreotype developed?
answers: 1839