Cyanotype is a 170 year old photographic printing process, it produces prints in a distinctive dark greenish-blue. The process was invented by Sir John Herschel, in 1842, however Herschel didn't use the process for photography, instead he used it for reproducing notes. It was Anna Atkins who first used it as a printing process in 1843. She created her images by placing objects directly on photosensitive paper; this process is called photogram. Compared to other photographic printing processes, cyanotype is easy and inexpensive, it uses sun and iron salt solutions, ferric ammonium citrate and potassium ferricyanide are combined, and exposure to UV light creates ferric ferrocyanide, also knows as prussian blue. You apply the chemical solution to paper, once dried, specimens could then be placed on top. Left to expose in sunlight, the paper turns a deep blue colour, leaving only the white silhouetted shape of the objects. The advantages of cyanotypes are that they are cheap and easy to use, it doesn't require and complicated equipment meaning that anyone can do it if they wanted to.
Anna Atkins
Anna Atkins (1799-1871) was a english photographer and botanist. She was considered to have been the first female photographer. In the mid 19th century she had created at least 10,000 images by hand, which all consist of various plants. She created/wrote many books in her life and only 13 of them are known to exist, some of which are in various stages of completion. She was introduced to photography by her father. He was a chemist, mineralogist and zoologist. She was surrounded by science and also contributed in some of her fathers works.