A darkroom is a workspace, usually a separate area in a building or a vehicle, made dark to allow photographers to use light-sensitive materials to develop film and photographic paper to make photographic prints. Darkrooms have been in use since the late 19th century for black and white photography. Using black and white film, photographers could control every step of the photographic process.
Due to the complexity of processing colour film (see C-41 process) and printing color photographs, and to the rise, first of Polaroid technology and later digital photography, darkrooms are decreasing in popularity.
The darkroom does not have to be completely dark when making black and white prints. Most black and white print papers are only sensitive to blue light, or to blue and green light, so black and white darkrooms feature a specially-made red or amber coloured light, known as a safelight. It enables the photographer to work in the light so they can see what they are doing, without exposing the paper. A low-intensity orange or yellow light can also be used, but these are less common than the red safelight. Colour print paper, on the other hand, is sensitive to all parts of the visible spectrum and therefore must be kept in complete darkness until the prints are properly fixed. There is however a very dim amber safelight that can be used in colour photography, but it is so dim as to be of little use. For both colour or black and white paper, a "paper-safe" -- a light-proof box to safely store photographic paper not in use as opposed to the boxes and light-proof bags that the paper comes packaged in -- can be used.
Another use for a darkroom is to load film in and out of cameras, development spools, or film holders, which requires complete darkness. Lacking a darkroom, a photographer can make use of a changing bag, which is a small bag with sleeved arm holes specially designed to be completely light proof and used to prepare film prior to exposure or developing.
During exposure, values in the image can be adjusted, most often by "dodging" (reducing the amount of light to a specific area of an image by selectively blocking light to it for part or all of the exposure time) and/or "burning" (giving additional exposure to specific area of an image by exposing only it while blocking light to the rest). Filters, or thin pieces of colored plastic, can be used to increase or decrease an image's contrast, or the difference between dark tones and light tones. After exposure, the photographic printing paper (which still appears blank) is ready to be processed.
Note that some photographers who use large format (usually defined as 4x5" and larger sized film) cameras do not necessarily need to enlarge an image, but are able to produce a same sized print by placing the negative directly on top of the paper, usually pressing it down tight with glass. This is known as a contact print.
The paper that has been exposed by enlargement or by contact exposure needs to then be processed in order to become a permanent, viewable print.
For black-and-white images, this process is comprised at a minimum of four chemical steps: (1) development of the print in a photographic developer; (2) stopping of image development by water rinse or use of special stop bath); (3) "fixing" (making the image permanent and removing its light-sensitivity) of the image in a photographic fixer; then (4) washing of the print in order to remove the processing chemicals. This is followed by drying the print. There are a variety of other, additional steps a photographer may take, such as toning.