The Force is what gives the Jedi his power. The Jedi can feel The Force flowing through him.
The Force can have a powerful effect on the weak minded.
George Lucas made three good movies about The Force but became so full of shit he started making toy marketing tie-in movies starring such offensive cuteness as Ewoks and equally offensive ugliness as Jar Jar Binks.
And the midichlori- That word doesn't exist.
Mormon science fiction writer Orson Scott Card said of The Force that "It's one thing to put your faith in a religion founded by a real person who claimed divine revelation, but it's something else entirely to have, as the scripture of your religion, a storyline that you know was made up by a very nonprophetic human being."
Similarities in household items
Duct tape is like the Force. It has a light side, it has a dark side, and it holds the galaxy together.
In another galaxy far, far away
The Force is named there Schwartz and has an upside and a downside. Can be channeled with Schwartz-rings or even in the case of those who have it within them without the help of said devices to produce the same effects as the Force, including energy swords projected from... interesting places, and is a very good fuel for spacecraft engines.