Does karma exist?

We constantly hear the word 'karma' in conversations without knowing the true meaning of the words. Primarily, it's important to follow the principle of treating others as u would like to be treated. In other words, if u do bad things to others, it'lll return to u just like "what goes around comes around". There's a reaction to everything u do in life.
So anger begets anger, love begets love, hate begets hate. I know this sounds simplistic and kinda irrasional but who knows exactly if karma does exist :P Simply refers to the process of cause and effect. 
Just remember that....
1. somebody's gonna give u a lesson in leavin'
2. somebody's gonna give u back what u've been givin'
3. somebody's gonna give u a lesson in losin'
4. somebody's gonna do to u what u've been doin'
5. somebody's gonna give u a lesson in hurtin' 

-DD-