Karma is a concept in Asian religions such as Hinduism, Jainism and Buddhism that are sympathetic to the ideas of reincarnation or rebirth (the Buddhist concept of rebirth should not be confused with reincarnation!). It is held to represent the "balance" of good and bad acts we have performed in this lifetime and others.
Karma is sometimes translated as "cause and effect", but this is not quite correct. Karma is cause, vipaka (Sanskrit and Pali vipâka) is effect; cause and effect is karma-vipaka, not only karma.
According to [Hindu]Karma, performing meritorious acts results in rebirth into a higher station, such as a superior human being or a godlike being, while evil acts result in rebirth as a human living in less desirable circumstances, or as a lower animal. While the action of karma may be compared with the Western notions of sin and judgment by God or gods, karma is held to operate as an inherent principle of the Universe without the intervention of any supernatural being.
Most teachings say that for common mortals, having an involvement with Karma is an unavoidable part of day-to-day living. However, in the Buddha's teachings, as well as in Vedanta and Shaivism, one is advised to either avoid, control or become aware of the effects of desires and aversions as a way to moderate or change one's karma.
In Buddhism, only intentional actions are karma; in Jainism, unintentional action are so too. Hinduism has several different ideas of karma, not necessarily compatible with each other.
In Sanskrit, the word Karma is defined as action. There is an understanding implied that action causes re-action or an effect (Vipaka). The re-action or effect can itself also become an action, and, in this way, the chain of causation may continue ad infinitum. There is no belief in the earliest definitions of karma that there is any kind of punishment attendant on actions that are performed. However, it was also believed that Intent is an action in itself, and could be even more powerful than a physical action.
The idea of karma was popularized in the west through the work of the Theosophical Society. Western New Age reinterpretations of karma frequently cast it as a sort of luck which is associated with virtue: if one does good or spiritually valuable acts, one deserves and can expect good luck; contrariwise, if one does harmful things, one can expect bad luck or unfortunate happenings. In this conception, karma is affiliated with the Neopagan law of return or Threefold Law, the idea that the beneficial or harmful effects one has on the world will return to oneself.
The Pali language form of the word, transliterated as kamma, is used in the Pali Canon of Buddhist scriptures.