His Holiness the Dalai Lama from 'The Buddhism of Tibet'“The Sanskrit word Karma (or kamma in Pali) literally means action. In Buddhism however, karma mainly refers to one's intention or motivation while doing an action.
The shortest explanation of karma that I know is: 'you get what you give'. In other words; whatever you do intentionally to others, a similar thing will happen to yourself in the future.
Our largest obstacle to understanding or even believing in karma may be time. The 're-actions' or results of our actions show up with a time delay, and it becomes extremely hard to tell which action caused which result. For ordinary humans, the mechanisms of karma can be intellectually understood to some extent, but never completely "seen".May anyone who merely sees or hears,
remembers, touches or talks to me,
be instantly freed from all sufferings
and abide in happiness forever.
May all sentient beings have equanimity, free from attachment, aggression and prejudice.
May they be happy, and have the causes for happiness.
May they be free from suffering and causes for suffering.
May they never be separated from the happiness that is free from suffering.