Karma (Sanskrit: कर्म , "act, action, performance; Pali: kamma) is the concept of "action" or "deed" in Indian religions understood as that which causes the entire cycle of cause and effect (i.e., the cycle called saṃsāra) originating in ancient India and treated in Hindu, Jain, Sikh and Buddhist philosophies.
The philosophical explanation of karma can differ slightly between traditions, but the general concept is basically the same. Through the law of karma, the effects of all deeds actively create past, present, and future experiences, thus making one responsible for one's own life, and the pain and joy it brings to him/her and others. The results or 'fruits' of actions are called . In religions that incorporate reincarnation, karma extends through one's present life and all past and future lives as well.
The Esoteric Christian tradition, Essenian and later Rosicrucian schools teach it as the "Law of Cause and Consequence/Effect". However, this western esoteric tradition adds that the essence of the teachings of Christ is that the law of sin and death may be overcome by the Love of God, which will restore immortality. Basically, what one does in the past affects one's future: performing good deeds will result in good effects and performing bad deeds will result in bad effects.
Karma means "deed" or "act" and more broadly names the universal principle of cause and effect, action and reaction that governs all life. Followers of Vedanta consider Ishvara, a personal supreme God, as playing a role in the delivery of karma. Theistic schools of Hinduism such as Vedanta thus disagree with the Buddhist and Jain views and other Hindu views that karma is merely a law of cause and effect but rather is also dependent on the will of a personal supreme God. Examples of a personal supreme God include Shiva in Shaivism or Vishnu in Vaishnavism. A good summary of this theistic view of karma is expressed by the following: "God does not make one suffer for no reason nor does He make one happy for no reason. God is very fair and gives you exactly what you deserve."
Karma is not fate, for humans act with free will creating their own destiny. According to the Vedas, if we sow goodness, we will reap goodness; if we sow evil, we will reap evil. Karma refers to the totality of our actions and their concomitant reactions in this and previous lives, all of which determines our future. The conquest of karma lies in intelligent action and dispassionate response.
Karma is considered to be a spiritually originated law. Many Hindus see God's direct involvement in this process, while others consider the natural laws of causation sufficient to explain the effects of karma. Karma is not punishment or retribution but simply an extended expression or consequence of natural acts. The effects experienced are also able to be mitigated by actions and are not necessarily fated. That is to say, a particular action now is not binding to some particular, pre-determined future experience or reaction; it is not a simple, one-to-one correspondence of reward or punishment.
Hindu scriptures divide karma into three kinds: Sanchita (accumulated), Prarabdha (fruit-bearing) and Kriyamana (current) karma. All kriyamana karmas become sanchita karma upon completion. From this stock of sanchita karma, a handful is taken out to serve one lifetime and this handful of actions, which has begun to bear fruit and which will be exhausted only on their fruit being enjoyed and not otherwise, is known as prarabdha karma. In this way, so long as the stock of sanchita karma lasts, a part of it continues to be taken out as prarabdha karma for being enjoyed in one lifetime, leading to the cycle of birth and death. A Jiva cannot attain moksha until the accumulated sanchita karmas are completely exhausted.
Within Sikhism, all living beings are described as being under the influence of Maya's three qualities namely Rajas (mode of passion), Tamas (mode of ignorance), and Saatav (mode of goodness). Always present together in varying mix and degrees, these three qualities of Maya bind the Soul to the body and to the earth plane. Above these three qualities is the eternal time. Due to the influence of three modes of Maya's nature, jivas (individual beings) perform activities under the control and purview of the eternal time. These activities are called Karma. The underlying principle is that karma is the law that brings back the results of actions to the person performing them.
This life is likened to a field (Khet) in which our Karma is the seed. We harvest exactly what we sow. No less, no more. This infallible law of Karma holds everyone responsible for what the person is or going to be. Based on the total sum of past Karma, some feel close to the Pure Being in this life, and others feel separated. This is the Gurbani's (Sri Guru Granth Sahib, SGGS) law of Karma. Like other Indian as well as oriental school of thoughts, the Gurbani also accepts the doctrines of Karma and reincarnation as the facts of nature.
Buddhism relates karma directly to motives behind an action. Motivation usually makes the difference between "good" and "bad", but included in the motivation is also the aspect of ignorance; so a well-intended action from a deluded mind can easily be "bad" in the sense that it creates unpleasant results for the "actor".
The last four cover "conditions" or "circumstances" in which karmic potential can ripen as a result.
Herman Kuhn quoting from Tattvarthasutra describes karmas as – a mechanism that makes us thoroughly experience the themes of our life until we gained optimal knowledge from them and until our emotional attachment to these themes falls off.
According to Padmanabh Jaini "this emphasis on reaping the fruits only of one’s own karma was not restricted to the Jainas; both Hindus and Buddhist writers have produced doctrinal materials stressing the same point. Each of the latter traditions, however, developed practices in basic contradiction to such belief. In addition to shrardha (the ritual Hindu offerings by the son of deceased), we find among Hindus widespread adherence to the notion of divine intervention in ones fate, while Buddhists eventually came to propound such theories like boon-granting bodhisattvas, transfer of merit and like. Only Jainas have been absolutely unwilling to allow such ideas to penetrate their community, despite the fact that there must have been tremendous amount of social pressure on them to do so."
The key points where the theory of Karma in Jainism differs from the other religions, can be stated as follows:
Karma does not specifically concern itself with salvation as it implies a basic socio-ethical dynamic. The law of karma as a mechanism functions like a judge of one's actions, similar to the concept of God as judge in relation to "good and bad works" in the western religions. The Apostle Paul similarly states: "man reaps what he sows" 
Similarly, the Egyptian goddess Ma'at (the divine judge) played a similar and impartial role meting out justice in a manner very similar to karma; Ma'at could not be appeased by faith or regret — an action done was done, with no space for the more recent theistic concept of grace.
Parallels may also be found in the Greek goddess Ananke (Necessity, Inevitability, or Compulsion), who was the mother of the Moirae (Fates) and dealt out one's "heimarmene" (allotted portion) strictly according to one's actions both in this life and in previous incarnations, and in Germanic Wyrd.
According to karma, performing positive actions results in a good condition in one's experience, whereas a negative action results in a bad effect. The effects may be seen immediately or delayed. Delay can be until later in the present life or in the next. Thus, meritorious acts may mean rebirth into a higher station, such as a superior human or a godlike being, while evil acts result in rebirth as a human living in less desirable circumstances, or as a lower animal. Some observers have compared the action of karma to Western notions of sin and judgment by God or gods, while others understand karma as an inherent principle of the universe without the intervention of any supernatural Being. In Hinduism, God does play a role and is seen as a dispenser of karma; see Karma in Hinduism for more details. The non-interventionist view is that of Buddhism and Jainism.
Most teachings say that for common mortals, being involved with karma is an unavoidable part of daily living. However, in light of the Hindu philosophical school of Vedanta, as well as Gautama Buddha's teachings, one is advised to either avoid, control or become mindful of the effects of desires and aversions as a way to moderate or change one's karma (or, more accurately, one's karmic results or destiny).
What sets Spiritism apart from the more traditional religious views is that it understands karma as a condition inherent to the spirit, whether incarnated or not: the consequences of the crimes committed by the spirit last beyond the physical life and cause him (moral) pain in the afterlife. The choice of a life of hardships is, therefore, a way to rid oneself of the pain caused by moral guilt and to perfect qualities that are necessary for the spirit to progress to a higher form.
Because Spiritism always accepted the plurality of inhabited worlds, its concept of karma became considerably complex. There are worlds that are "primitive" (in the sense that they are home to spirits newly born and still very low on intellect and morals) and a succession of more and more advanced worlds to where spirits move as they are elevated. A spirit may choose to be born on a world inferior to his own as a penance or as a mission.