The Force binds the universe together. Like Duct tape. It has a Dark side and a Light side. Like Duct tape. The Force is NOT Duct tape. We think.
The Light Side
Also know as what the good guys do. It is used for knowledge and defense, never for attack. Unless you are attacking "Bad Guys" like storm troopers, Imperial Officers, anyone who works for the government in any capacity, gangsters and anyone that has ever been associated with gangsters(Unless they are good guys). Jedi used the Light side and claimed that it was as powerful or more powerful than the dark side. Then again an old man and a guy with no limbs using the dark side managed to kill all but two of the Jedi. So who knows.
The Dark Side
Anybody considered evil or bad uses the dark side. They are also always infinitely cooler than the good guys, unless said good guy used to be a bad guy. Sometimes good guys use the Dark side even though it is forbidden but as long they act contrite afterward all is forgiven. The dark side gets the cool stuff like lighting and red lightsabers, plus they can choke you from across the room and anyone who had a younger sibling knows how awesome that would be "I didn't touch them!". Awesome. Dark side guys claim its more powerful and considering that all known people that turn to the dark side become more powerful right afterward it seems to be true. Then again the two most powerful Dark side users ever were beaten by a punk kid that made his daddy feel sad. F*ing weak.
Qui-Gon Jinn used to convince his padawans that all force sensitive beings had midi-clorians that when counted told you how powerful you would be in the force. This was just a practical joke and it was never mentioned again after he got killed.