Kamma is not fate nor predestination. It literally means action , that is volitional action. A deed done deliberately through body, speech or mind. Every volitional action (except that of a Buddha or of an Arahant) is called Kamma.. Kamma constitutes both good and evil. volition (kusala Akusala Centana). Good gets good. Evil gets evil. Like attracts like..

In other words, Karma is the law of moral causation. It is action and reaction in the ethical realm. It is natural law that every action produces a certain effect. So if one performs wholesome actions such as donating money to charitable organisations, one will experience happiness. On the other hand, if one perform unwholesome actions, such as killing a living being, one will experience suffering. This is the law of cause and effect at work. In this way, the effect of ones past kamma determine the nature of ones present situation in life. This is a universal principle, on which Buddhist morality is based.

The Buddha said, "According to the seed that is sown, So is the fruit you reap The door of good will gather good result The door of evil reaps evil result. If you plant a good seed well, Then you will enjoyed the good fruits."

This is the law of Kamma

There are three kinds of Kamma:

Good Kamma (Kusala)
It means intelligent, or skillful. It refers to those intentional actions, which are beneficial to oneself and others, springing out from kindness, compassion, renunciation and wisdom.

Bad Kamma (Akusala)
It means not intelligent, not skillful. It refers to those intentional action springing out from greed, hatred and illusion.

Neutral Kamma (Centana)

For unintentional actions, such as walking, sleeping, breathing, they have no moral consequences, thus constitute neutral Karma or ineffective Karma.

While Buddhism attributes variation to Kamma, it does not assert that everything is due to Kamma. If everything were due to Kamma, a man must ever be bad, for it is his Kamma to be bad. One need not consult a physician to be cured of a disease, for if one's Kamma is such one will be cured.
According to Buddhism, there are five orders or processes (Niyamas) which operate in the physical and mental realms:
i. Kamma Niyama, order of act and result, e.g., desirable and undesirable acts produce corresponding good and bad results.
ii. Utu Niyama, physical (inorganic) order, e.g., seasonal phenomena of winds and rains.
iii. Bija Niyama, order of germs or seeds (physical organic order); e.g., rice produced from rice-seed, sugary taste from sugar cane or honey etc. The scientific theory of cells and genes and the physical similarity of twins may be ascribed to this order.
iv. Citta Niyama, order of mind or psychic law, e.g., processes of consciousness (Citta vithi), power of mind etc.
v. Dhamma Niyama, order of the norm, e.g., the natural phenomena occurring at the advent of a Boddhisatta in his last birth, gravitation, etc.
Every mental or physical phenomenon could be explained by these all-embracing five orders or processes which are laws in themselves.
Kamma is, therefore, only one of the five orders that prevail in the universe. It is a law in itself, but it does not thereby follow that there should be a law-giver. Ordinary laws of nature, like gravitation, need no law-giver. It operates in its own field without the intervention of an external independent ruling agency.
Nobody, for instance, has decreed that fire should burn. Nobody has commanded that water should seek its own level. No scientist has ordered that water should consist of H2O, and that coldness should be one of its properties. These are their intrinsic characteristics. Kamma is neither fate nor predestination imposed upon us by some mysterious unknown power to which we must helplessly submit ourselves. It is one's own doing reacting on oneself, and so one has the possibility to divert the course of Kamma to some extent. How far one diverts it depends on oneself.
It must also be said that such phraseology as rewards and punishments should not be allowed to enter into discussions concerning the problem of Kamma. For Buddhism does not recognize an Almighty Being who rules His subjects and rewards and punishes them accordingly. Buddhists, on the contrary, believe that sorrow and happiness one experiences are the natural outcome of one's own good and bad actions. It should be stated that Kamma has both the continuative and the retributive principle.
Inherent in Kamma is the potentiality of producing its due effect. The cause produces the effect; the effect explains the cause. Seed produces the fruit; the fruit explains the seed as both are inter-related. Even so Kamma and its effect are inter-related; "the effect already blooms in the cause."
A Buddhist who is fully convinced of the doctrine of Kamma does not pray to another to be saved but confidently relies on himself for his purification because it teaches individual responsibility.
It is this doctrine of Kamma that gives him consolation, hope, self reliance and moral courage. It is this belief in Kamma "that validates his effort, kindles his enthusiasm," makes him ever kind, tolerant and considerate. It is also this firm belief in Kamma that prompts him to refrain from evil, do good and be good without being frightened of any punishment or tempted by any reward.
It is this doctrine of Kamma that can explain the problem of suffering, the mystery of so-called fate or predestination of other religions, and above all the inequality of mankind.