The effect of karma and the Rebirth:

Now as a man is like this or like that, according as he acts and according as he behaves, so will he be; a man of good acts will become good, a man of bad acts, bad; he becomes pure by pure deeds, bad by bad deeds; And here they say that a person consists of desires, and as is his desire, so is his will; and as is his will, so is his deed; and whatever deed he does, that he will reap.- Brihadaranyaka Upanishad

The relationship of karma to causality is a central motif in all schools of Hindu, Jain and Buddhist thought. The theory of karma as causality holds that executed actions of an individual affects the individual and the life he or she lives, and the intentions of an individual affects the individual and the life he or she lives.

Disinterested actions or unintentional actions do not have the same positive or negative karmic effect, as interested and intentional actions. In Buddhism, for example, actions that are performed, or arise, or originate without any bad intent such as covetousness, are considered non-existent in karmic impact or neutral in influence to the individual.

Another causality characteristic, shared by Karmic theories, is that like deeds lead to like effects. Thus good karma produces good effect on the actor, while bad karma produces bad effect. This effect may be material, moral or emotional that is, one's karma affects one's happiness and unhappiness. The effect of karma need not be immediate; the effect of karma can be later in one's current life, and in some schools it extends to future lives.

The consequence or effects of one's karma can be described in two forms: phalas and samskaras-effect. A phala-results (literally fruit or result) is the visible or invisible effect that is typically immediate or within the current life. In contrast, samskaras are invisible effects, produced inside the actor because of the karma, transforming the agent and affecting his or her ability to be happy or unhappy in this life and future ones. The theory of karma is often presented in the context of samskaras.

Karmic principle can be understood as a principle of psychology and habit. Karma seeds habits (Vasana), and habits create the nature of man. Karma also seeds self perception, and perception influences how one experiences life events. Both habits and self-perception affect the course of one's life. Breaking bad habits is not easy: it requires conscious karmic effort.

Thus psyche and habit, according to Potter and others, link karma to causality in ancient Indian literature. The idea of karma may be compared to the notion of a person's "character", as both are an assessment of the person and determined by that person's habitual thinking and acting.

Rebirth

The third common theme of karma theories is the concept of reincarnation or the cycle of rebirths (saṃsāra).

Rebirth is a fundamental concept of Hinduism, Buddhism, Jainism and Sikhism. The concept has been intensely debated in ancient literature of India; with different schools of Indian religions considering the relevance of rebirth as either essential, or secondary, or unnecessary fiction.

Rebirth, or saṃsāra, is the concept that all life forms go through a cycle of reincarnation that is a series of births and rebirths. The rebirths and consequent life may be in different realm, condition or form. The karma theories suggest that the realm, condition and form depend on the quality and quantity of karma. In schools that believe in rebirth, every living being's soul transmigrates (recycles) after death, carrying the seeds of Karmic impulses from life just completed, into another life and lifetime of karmas. This cycle continues indefinitely, except for those who consciously break this cycle by reaching Moksha. Those who break the cycle reach the realm of gods, those who don't continue in the cycle.