Describe the history, process, and importance of photogravure.

Process- It's an intaglio printmaking process in which a copper plate is coated with a light-sensitive gelatin tissue which has been exposed to a film positive, and then etched, resulting in a high quality intaglio print that can reproduce the detail and continuous tones of a photo. 
History- It was invented by William Henry Fox Talbot and Karel Klic (key inventors). Patents by Talbot. Never patented by Klic, but some process variants patented later (1879).
Importance- It was one of the earliest experiments in transferring photographic images onto paper. It's also played an important role in many photographers and publishers missions.