The word 'karma' literally means 'action' or 'to do'. In Buddhism, however, the word is used to mean volitional, or intentional, actions.
In the Buddhist view, all creatures are caught in samsara- the endless chain of birth, death and rebirth. That which determines our capture in this chain is our karma, past and present. Past karma has an effect on our present situation in life and the difficulties or advantages we have experienced, and this karmic cause-and-effect is entirely our own fault and responsibility, not the whim of any divine being.
Types of Karma
Karma can be divided into two main types - skilful and unskilful karma - and each intentional action that you take will bring about a similarly skilful or unskilful effect in time. All of our unskilful karma comes from the three fires that are inherent in our nature: greed, hatred and ignorance. It is possible to extinguish these fires through mindfulness and selflessness, but in the acceptance that we are unlikely to achieve this entirely without leading a monastic life it is important to note that we can perform skilful actions despite the tendency to act unskilfully being inherent in all creatures. Skilful actions often derive from giving (be it the giving of a material object such as money, or a spiritual object such as hope), goodwill and mindfulness. Buddhists see that there are three doors through which we act and generate karma: body, speech and mind. In accordance with this system we generate skilful or unskilful karma even from thinking of performing wholesome or unwholesome actions.
To clarify; examples of unskilful actions of the body may include stealing and physical violence where skilful actions of the body may include giving and self-control. Karma is not set in stone and we cannot make actions black or white, hence why Buddhists will not refer to 'good' or 'bad' karma, but 'skilful' and 'unskilful' karma, with the intention of implying that you can improve your karmic action as you would any other skill. Buddhists acknowledge karma as being dependant on the intent of the creature. There is a third type of karma that may also be noted; this is neutral karma - karma that is bereft of intent and has little moral implication. Examples of this may include breathing and walking.
The Wider Implications of Karma
One may wonder about the wider implications of karma. Karma may easily be looked at from this point without applying any form of religious belief. Indeed, it may be easier to understand the implication of karma from this viewpoint, by looking at it as simple cause and effect. If one was to harbour unskilful thoughts, such as anger and hatred it is inevitable that they will turn to unskilful speech, such as malicious gossiping and lying. This will eventually cause hurt and suffering to the object of your hatred. Once one has established one's self as a malicious gossip or one who causes upset to others it is likely that one may be alienated from one's social circle and will eventually find one's self alone and the victim of similar malicious gossip. In this way, if one performs an unskilful karmic action one will eventually suffer the effects of this action. In Buddhist terms we do not always experience the effects of our skilful or unskilful karma in this life, but will work off or enjoy the effects of our karma in that which we face in future rebirths. A higher stockpile of skilful karma will lead to more comfortable rebirths whereas a higher stockpile of unskilful karma will result in a less comfortable rebirth.
Due to the highly personal nature of karma, it is important to note that there are five conditions that alter the weight or significance of the karma generated. If your actions are performed repeatedly they are more significant. The presence or absence of regret in performing an action changes the weight of the karma. When an action is performed on those who posses extraordinary qualities, such as a Buddha (enlightened being), the karmic weight is increased. If the action is performed on someone who has benefited you in the past, such as a teacher or a parent, the karmic weight is increased. When the action is done with great determination or with exceptional intent the karmic weight is increased.
It is impossible for us to tell what the results of any past karma manifest as, but it is not wise to blame a situation on karma and claim no responsibility for it as karma is not a form of destiny or fate, it is simply the medicine you prescribe for yourself.