What is a Cyanotype?

So I realized that I had gone on and on about a process and that some people may have no clue what it is. So here you go:
A cyanotype print, unlike traditional photographs set in a light reactive silver, use a solution of iron compounds to create the image. Its the oxidation of these compounds during the exposure and washing process that create the blue image.
The cyanotype is also where the term "blue print" comes from. It is the process that was used to create the blueprint drawings before all this fancy technology we have today. Artists just took use of its light reactive properties and tweaked it for their uses.