Karma in Buddhism

Karma. Simply stated, karma means that one is morally responsible for one's actions. It literally means, "action," (Sanskrit; Pali kamma) and volition is its essence. Buddhist thinking recognizes that all current actions are conditioned by previous actions, and teaches the importance of applying volition choicefully. Classically, karma includes the concept of rebirth; practically, it emphasizes the moment-to-moment actions of daily life.
In its simplest form, we can recognize that past actions affect current behaviour. Refusing to "buckle up" can result in head injury if there's an accident. A scholarship could be awarded to a student who chose study over socializing. Having too many cocktails can mean a period of months without a driver's license.
Mindfulness provides the means by which we can choose skillful or wholesome actions, rather than actions conditioned by previous events. For example, in the midst of rush-hour freeway traffic a car in the right lane cuts in front of a hurried driver in the centre lane without signalling the lane-change. It's not uncommon to utter a snarl and honk the horn - both unskillful actions done in anger. And a moment later, when another car signals from the left, wishing to merge into the centre lane, it's most likely that the centre-lane driver will refuse to yield. Rather, the driver may move closer to the car in front, denying space to the merging vehicle. The unskillful action of refusing to yield has resulted from the anger of the previous action! Mindfulness makes room for practical alternatives to unskillful actions.