Kodachrome
Brand name for a non-substantive, color reversal film introduced by Eastman Kodak in 1935.
Kodachrome is a discontinued color slide film. This means that it produces a positive, true-color image on the film rather than a negative like the common C-41 film. It was made by Kodak from 1935 to 2009. It had a complex developing process called K-14. It had to be developed in a lab dedicated to this process. The last lab developing Kodachrome in color closed in 2010, although there are still several labs that can develop it in black and white.
See also
changeEktachrome is a similar film that also produces a positive image, but has a much simpler development process.