What is karma? The literal Sanskrit meaning of karma is action. For every action, no matter how insignificant, there is a reaction (whether it be action in deeds, words, and even thought or even as simple as breathing the air we breath), and one is bound to the outcome of these reactions.
Hinduism holds that as long as one perceives duality (that of subject and object), one is bound to ones karma. One is released from this bondage when he realizes his true nature, as the Atman (and vice versa, when he removes himself from bondage he realizes his true nature).
Because the impending reaction to ones actions may not take place immediately, but is usually deferred to a later time, karma is often mistaken for “fate”. One’s karmas (the reactions that are pending to the actions one has created) may accumulate over a long period (including over lifetimes), and may manifest itself in the most unexpected way at the most unexpected time. Thus it looks like it is preordained, whereas in reality it is one’s own doing. Hinduism lays emphasis on destiny (via one’s cosmic dharma), not on fate. Destiny is not just ones karma, but the collective karma of the universe – the cosmic direction, purpose, dharma, or grand plan of the universe.
Karma does not come back to hit us at an individual level in as much as it does at the cosmic level. According to Hindu yogis we are all part of one cosmic consciousness. Everything is pure consciousness. So the impact of every thought, good or bad, has a ripple effect. For example, if we abuse the environment, then what we destroy will come back to haunt us (in ways ranging from hurricanes to diseases). As we sow thus we shall reap. This is not about some apocalyptic judgement day, but a law of natural order.
What is Action?
Before we even think about talking about action (and its consequences), just what is action? isn’t in-action or non-action also an action? Isn’t the decision to not act, also an action, as it is to act (reminds me of standing wave patterns/equations in physics; a simple example is the ripples on the surface of a lake – they move, yet the pattern remains still).
किं कर्म किम् अकर्मेति कवयो अप्य् अत्र मोहिताः ।
तत् ते कर्म प्रवक्ष्यामि यज् ज्ञात्वा मोक्ष्यसे अशुभात् ।।
“What is action? What is inaction?” Thus, even the Great Ones (the sages/yogis) are confused in this matter.
This action I shall explain to you, having known which, you shall be released from this [cycle].
– Bhagavad Gita, 4.16
The next few stotras in Book 4 of the Bhagavad Gita, further engages us on a deeper philosophical level as to just what is action, non-action, wrong action (“wrong action” is a very loose translation of vikarmana), and our perception of duality which makes us waste time on such mundane things. That is, the concept of “action” itself being created because of giving importance to human-level perception. Such words have no meaning once one goes beyond subject and object (when one sees both as one).