By definition, Karma is the total effect of a person's actions and conduct during the successive phases of the person's existence, regarded as determining the person's destiny.
Too cheem to understand? Karma is something like, if you did something good, you will be awarded for your good deeds, and if you did something bad, you will be punished for your evil deeds. You will be awarded or be punished for your deeds either in this life or in your future existence.
I believe Karma applies to every religions in the world. Just that how the followers of different religions see it.
As a Buddhist, I believe in Karma, the cause and effect.
I ain't sure this is true or not, sometimes I do believe that I am being rewarded and punished for my past deeds. True story.
The Story: Cause
When yours truly was still a young boy in Myanmar, mom got me a bread loaf one day. Yeah, I took a bite or do and I was full. I never did like to eat bread. And it is a waste to throw away the bread since it was still fresh and a large portion was uneaten. Then there was this young novice monk who was on his way for daily alms begging. At the moment, I was either out of my mind or I am not sure why, I just donated the remaining loaf to the monk. I swear, it was not intentional. I did not intend to donate my leftover food to him. I just donated the food to the young monk. I did not realize until a moment later and yeah, that was one of the regret of life.
Consequences: Effect
Because of the good deed, the deed of donating the food to the monk, I enjoying myself with variety of food and never would I have to worry about getting hungry. But, I could not run away from bad karma. I would still be punished. I realised that I would be forced to eat the leftover food every time that damn uncle of mine could not finish or purposely left the portion of the food he do not want to eat. I would deny most of the time but to no avail, I have no say. I could not throw tantrum at him, hurl vulgarities at him because I am depending on him for my living in Singapore. Most of the time, I would have to eat it even though it was unfair. Fearful isn't it?
Well, was it me or I am paying for my Karma? No one really knows, only the higher beings would know.
"I am the owner of my karma .
I inherit my karma.
I am born of my karma.
I am related to my karma.
I live supported by my karma.
Whatever karma I create, whether good or evil, that I shall inherit."
The Buddha, Anguttara Nikaya V.57 - Upajjhatthana Sutta
Readers, don't ever underestimate the Karma.
Signing Off.