Rollfilm or roll film is any type of spool-wound photographic film

Photographic film

Photographic film is a sheet of plastic coated with an emulsion containing light-sensitive silver halide salts with variable crystal sizes that determine the sensitivity, contrast and resolution of the film...

 protected from white light

White Light

White Light may refer to:*Light with the color white*White Light , a 1980 novel by Rudy Rucke*White Light , 1971 album*White Light , 2010 album...

 exposure by a paper backing, as opposed to film which is protected from exposure and wound forward in a cartridge. Confusingly, roll film was originally often referred to as "cartridge" film because of its resemblance to a shotgun

Shotgun

A shotgun is a firearm that is usually designed to be fired from the shoulder, which uses the energy of a fixed shell to fire a number of small spherical pellets called shot, or a solid projectile called a slug...

 cartridge. The opaque backing paper allows roll film to be loaded in daylight. It is typically printed with frame number markings which can be viewed through a small red window at the rear of the camera.