127 is a roll film, 46mm wide. Frame number markings for the 4×4 and 4×6 image formats are printed on the backing paper, while 4×3 cameras typically have two frame counter windows, exposing the left and right halves of the 4×6 frame.
Using the square format, there are 12 exposures per roll; 4×3 and 4×6 give 16 and 8, respectively.
There are alternative uses. For its "Alfax" model (circa 1940), Kimura had 4×4.5 cm frames, spaced by markings on the wind knob.
The format was introduced by Kodak in 1912, along with the "Vest Pocket Kodak" folding camera, as a compact alternative to larger portable cameras using 120. The folding "127s" were in fact smaller than most 35mm cameras today.
Not all 127 films were labeled as such. After 1913, many Kodak cameras included the Autographic feature, and Kodak's 127 films which had Autographic backing were identified as A127. Other film manufacturers did not produce Autographic films, for which Kodak held a patent. Other camera manufacturers did make Vest Pocket-format cameras, however, and 127 film at the time was often labeled "Vest Pocket Film."
The format was mainly used for amateur cameras, with the Exakta SLR, the "Baby" Rolleiflex and the Yashica 44 TLR and the Komaflex-S SLR as possible exceptions. Few photofinishers made enlargements at the time the film was introduced, and most 127 negatives were contact printed. The later, more expensive 127 cameras featured lenses that were good enough to permit enlargement.
127 color transparencies can be mounted in standard 2" square slide mounts, and projected in an ordinary 35mm projector. Because of their much greater area, the projected image is larger and more brilliant than a 35mm slide, and they are popularly called "Superslides," a name once reserved for 4x4 cm slides cut down from 120 film.
Kodak stopped producing 127 film in July, 1995, with all but one manufacturer following suit shortly thereafter. Fotokemika of Samobor, Croatia continued making 127 film, which it sells today under its own "Efke" brand as well as custom-packaging for other sellers. Macophot UP100 and Jessops 200 are made and packaged by Fotokemika. So is the "Chromazone" 127 film sold intermittently on eBay. In September of 2006, Bluefire Laboratories of Calgary, Alberta, Canada began packaging 127 color print film, cutting the film to size from bulk rolls made by established factories like Kodak and Agfa Gaevert, and assembling rolls of film from components made in Calgary.