The adoption of 35mm by manufacturers of cameras was a watershed in the history of photography to the point that this type of equipment is classified separately, not based on a particularly technical but according of its sensitive surface format.
In 1913, after several unsuccessful attempts by other manufacturers that Barmack Oscar (1879-1936), an engineer hired by Leitz, made the first 35 mm which was built in series from 1925: the "Leica". The success initially was not overwhelming but the constant improvement of the quality of the film providing the image size of 24 X 36 mm encourages the spread of this type of camera. The Leica quickly had its concurrants like to quote the toughest: the Contax I (1932) Zeiss Ikon and later, the Nikon I (1948) Nippon Kogaku.
The improvement of the film is thus accompanied by improvements such housings interchangeable lens, automatic diaphragms, telemeters, incorporated exposure meters, motors, removable back ... etc.
The 35mm camera is the type of camera that has been most used in the second part of the 20th century whether in non-SLR DSLR or SLR. It would be even if it was later supplanted by the digital camera.