Midi-CHLORians are one of the many types of tiny beings that live in your blood and bones and other cells. They pretty much live in every living bing and they love talking to you through the mysterious energies known as The Force.
They use Force push to push Force users to use the Force.
Midi-chlorians were intelligent microscopic life-forms that lived symbiotically inside the cells of all living things. When present in sufficient numbers, they could allow their host to detect the pervasive energy field known as the Force. Midi-chlorian counts were linked to potential in the Force, ranging from normal Human levels of 2,500 per cell to the much higher levels