The Micro Four Thirds (M4/3, Micro 4/3, or MFT) format is a digital sensor system originally introduced by Olympus and Panasonic in 2008. The system was developed as an advancement of Olympus’ Four Thirds system and was intended to minimize camera size without sacrificing image quality.
These Micro Four Thirds cameras were some of the first mirrorless cameras on the market. They were also easy to adapt lenses to, which renewed interest in vintage lenses. This is because of the short flange distance of the system. It’s possible to mount lenses from Canon, Leica, Nikon, Olympus, Pentax, and more without compatibility issues.