A darkroom is the room photographers use to develop their pictures. As the name suggests, the room is kept completely dark and, at most, only contains a safelight. The darkroom must be kept dark because it is here that a photographer will remove the film from the camera. Any light expose ti this film will ruin the recently taken photos.
After the film is removed in the darkroom, the photographer will treat it with a series of chemicals before printing it onto paper.
If a photographer is taking pictures on a digital camera however, his " darkroom" will likely involve computer software, such as Photoshop, where he can enchance, develop and print his photos.