The Cyanotype process is one of the oldest photographic processes known. It's been developed by John Herschel in 1842. The process yields a monochrom negative image. The most striking feature of the images is the deep blue tint.
This “special” colour of Cyanotypes may have led to the ignorance as a photographic art compared to other methods. But the Cyanotypes are able to yield results compareable to other fine print (or alternative) methods.
In one term the Cyanotype process still lives today: the term “blue print” originates in an industrial advanced method based on the Cyanotype process. Though Cyanotypes where not used in arts very often it's been around a long time for copying.