The self-controlled person, moving among objects, with his senses free from attachment and malevolence and brought under his own control, attains tranquility.
~ Bhagavad Gita II.64 s.

The law of cause and effect forms an integral part of Hindu philosophy. This law is termed as 'karma', which means to 'act'. The Concise Oxford Dictionary of Current English defines it as the "sum of person's actions in one of his successive states of existence, viewed as deciding his fate for the next". In Sanskrit karma means "volitional action that is undertaken deliberately or knowingly". This also dovetails self-determination and a strong will power to abstain from inactivity. Karma is the differentia that characterizes human beings and distinguishes him from other creatures of the world.

The Natural Law
The theory of karma harps on the Newtonian principle that every action produces an equal and opposite reaction. Every time we think or do something, we create a cause, which in time will bear its corresponding effects. And this cyclical cause and effect generates the concepts of (or the world) and birth and reincarnation. It is the personality of a human being or the jivatman - with its positive and negative actions - that causes karma.

Karma could be both the activities of the body or the mind, irrespective of the consideration whether the performance brings fruition immediately or at a later stage. However, the involuntary or the reflex actions of the body cannot be called karma.

Your Karma Is Your Own Doing
Every person is responsible for his or her acts and thoughts, so each person's karma is entirely his or her own. Occidentals see the operation of karma as fatalistic. But that is far from true since it is in the hands of an individual to shape his own future by schooling his present.

Hindu philosophy, which believes in life after death, holds the doctrine that if the karma of an individual is good enough, the next birth will be rewarding, and if not, the person may actually devolve and degenerate into a lower life form. In order to achieve good karma it is important to live life according to dharma or what is right.

Three Kinds of Karma
According to the ways of life chosen by a person, his karma can be classified into three kinds. The satvik karma, which is without attachment, selfless and for the benefit of others; the rajasik karma, which is selfish where the focus is on gains for oneself; and the tamasik karma, which is undertaken without heed to consequences, and is supremely selfish and savage.

In this context Dr. D N Singh in his A Study of Hinduism, quotes Mahatma Gandhi's lucid differentiation between the three. According to Gandhi, the tamasik works in a mechanic fashion, the rajasik drives too many horses, is restless and always doing something or other, and the satvik works with peace in mind.

Swami Sivananda, of the Divine Life Society, Rishikesh classifies karma into three kinds on the basis of action and reaction: Prarabdha (so much of past actions as has given rise to the present birth), Sanchita (the balance of past actions that will give rise to future births - the storehouse of accumulated actions), Agami or Kriyamana (acts being done in the present life).

The Discipline of Unattached Action
According to the scriptures, the discipline of unattached action (Nishkâma Karma) can lead to salvation of the soul. So they recommend that one should remain detached while carrying out his duties in life. As Lord Krishna said in the Bhagavad Gita: "To the man thinking about the objects (of the senses) arises attachment towards them; from attachment, arises longing; and from longing arises anger. From anger comes delusion; and from delusion loss of memory; from loss of memory, the ruin of discrimination; and on the ruin of discrimination, he perishes".