Karma and reincarnation
"The law of karma means the law of causation. This grand law includes the law of action and reaction, the law of compensation and the law of retribution." Swami Sivananda
The law of life
Karma means action; it refers to any physical or mental action as well as to the consequences of these actions. It is equivalent to the scientific law of cause and effect, or action and reaction.
The world runs according to this fundamental, vital law. The law of karma says that there is a specific cause behind everything that happens.
The fruits of karma
Desire creates karma. You work hard to gain what you desire. The fruit of karma is pleasure or pain. Man is reborn again and again to collect the fruits of his karma.