In the Star Wars universe, Midichlorian's are chemical compounds found within every living cell that forms the basis between the connection life and the Force. Without midichlorians, life would be impossible. According to Star Wars lore, the amount of midichlorians in a life from represents it's ability to understand, comprehend, and manipulate the Force.
According to Qui-Gon Jinn, in Star Wars Episode I: The Phantom Menace, Anakin Skywalker had the highest midichlorian count in any life form ever detected. That count was 20,000 per cell. This number was even higher than Yoda's.
However, one can only hypothesize how many midichlorians Anakin's son, Luke had.
Midichlorians fundamentally connect you to the Force.