Micro Four Thirds is a camera system standard, not just a sensor shape. It keeps the Four Thirds sensor size and 4:3 aspect ratio, but uses a much shorter flange focal distance (registration distance). That shorter distance helps make camera bodies and lenses smaller and lighter, which is a key reason manufacturers like Panasonic use it.

The “Four Thirds” part refers to the system and its 4:3 image aspect ratio. The older Four Thirds standard was designed around that format, and Micro Four Thirds evolved from it by removing the mirror box and shortening the lens mount distance.

In practical terms, Panasonic uses Micro Four Thirds because it enables more compact camera designs while still using the same sensor format and a shared lens ecosystem.