Karma refers to action driven by intention which leads to future consequences. From non-virtuous actions comes suffering and from virtuous actions comes happiness. Buddha gave extensive teachings that prove the truth of this statement. The purpose of understanding and believing in karma is to prevent future suffering and to establish the basic foundation for the path to liberation and enlightenment. The law of karma is a special instance of the law of cause and effect. The law of karma explains why each individual has a unique mental disposition, a unique physical appearance and unique experience. These are the various effects of the countless actions that each individual has performed in the past.
Karma has three components: action, their effects and the potentialities that actions leave in the mind. The potentiality ripens when the conditions are right, as a seed ripens in the spring when it receives the right amount of heat and moisture. Whether a potentiality is virtuous or non-virtuous, whether it ripens as happiness or suffering, depends upon the action.
Citation (MLA): Geshe Kelsang Gyatso. Joyful Path of Good Fortune. Glen Spey: Tharpa Publications, 1995.