What is karma?

Karma is the universal principle of cause and effect. Our actions, both good and bad, come back to us in the future, helping us to learn from life's lessons and become better people.

 Karma is one of the natural laws of the mind, just as gravity is a law of matter. Just as God created ‎gravity to bring order to the physical world, He created karma as a divine system of justice that is self-‎governing and infi nitely fair. It automatically creates the appropriate future experience in response ‎to the current action.‎

 Karma simply means "action" or "cause and effect." When something happens to us that is ‎apparently unfortunate or unjust, it is not God punishing us. It is the result of our own past actions. The Vedas,  ‎hinduism's revealed scripture, tell us if we sow goodness, we will reap goodness; if we sow evil, we ‎will reap evil. Thus we create our own destiny through thought and action. And the divine law is: ‎whatever karma we are experiencing in our life is just what we need at the moment, and nothing can ‎happen but that we have the strength to meet it. Even harsh karma, when faced in wisdom, can be ‎the greatest catalyst for spiritual growth. Understanding the way karma works, we seek to live a good ‎and virtuous life through right thought, right speech and right action. This is called dharma.‎
One of the best examples of karma is that you can't give anything away but that generosity will return to you, with interest. Here, in the upper scene, a lady happily gives clothing to a youth. Below, she receives an unexpected gift from a neighbor as the karma of her good deed brings its natural reward. By wisely heeding karma's ways, we tread the path of dharma.

Elaboration: Karma is basically energy. I throw energy out through thoughts, words and deeds, and ‎it comes back to me, in time, through other people. Karma is our best teacher, for we must always ‎face the consequences of our actions and thus improve and refine our behavior, or suffer if we do ‎not. We Hindus look at time as a circle, as things cycle around again. Professor Einstein came to the ‎same conclusion. He saw time as a curve, and space as well. This would eventually make a circle. ‎Karma is a very just law which, like gravity, treats everyone the same. Because we Hindus understand karma, we do not hate or resent people who do us harm. We understand they are giving back the effects of the causes we set in motion at an earlier time. The law of karma puts man at the center of responsibility for everything he does and everything that is done to him.‎

Karma is a word we hear quite often on television. "This is my karma," or "It must have been something I did in a past life to bring such good karma to me." We hear karma simply defined as "What goes around, comes around." In some schools of Hinduism, karma is looked upon as something bad—perhaps because we are most aware of this law when we are facing difficult karma, and not so aware of it when life is going smoothly. Even some Hindus equate karma with sin, and this is what evangelical Christians preach that it means.‎
Many people believe that karma means "fate," a preordained destiny over which one has no control,‎ which is also untrue. The process of action and reaction on all levels—physical, mental and ‎spiritual—is karma. Here is an example. I say kind words to you, and you feel peaceful and happy. I ‎say harsh words to you, and you become ruffled and upset. The kindness and the harshness will ‎return to me, through others, at a later time. This is karma. An architect thinks creative, productive ‎thoughts while drawing plans for a new building. But were he to think destructive, unproductive ‎thoughts, he would soon not be able to accomplish any kind of positive task even if he desired to do so. This is karma, a ‎natural law of the mind. We must also be very careful about our thoughts, because thought creates, ‎and thoughts make karmas—good, bad and mixed.‎