The Four Thirds system was created by Olympus and Eastman Kodak and was introduced in 2002. The Four Thirds Consortium consisted of the following companies: Olympus, Kodak, Leica, Fuji, Sigma, Panasonic and Sanyo. The majority of the Four Thirds cameras were made by Olympus but both Leica and Panasonic also released some models.

The Four Thirds system was discontinued in 2017 with the introduction of the newer Micro Four Thirds system, but the lenses are usable on Micro Four Thirds cameras using an adapter such as the Olympus MMF-3.