The Pàëi word kamma means `action' and in Buddhist doctrine refers to any intentional mental, verbal or bodily act. The effect or consequence of kamma is called vipàka. The Buddha said: `I say that intention is kamma, because having first intended one acts with body, speech or mind'(A.III,415). Every intentional action modifies our consciousness, thus building our character and thereby influencing our behaviour, our experience and our relationship to the world around us. Positive intentional actions (motivated by generosity, kindness, love and wisdom) tend towards consequences that are experienced as positive, while intentional negative actions (motivated by greed, hatred and delusion) tend towards consequences that are experienced as negative.

The doctrine of kamma is probably the most misunderstood of all the Buddha's teachings.  Some of the more common misunderstandings are these. (1) Some people have the impression that kamma is a force or energy in the universe independent of individuals but acting upon them. The Buddha made it clear that kamma is a function or characteristic of consciousness when he defined it as intention (cetana). He highlighted this point again when he said:`Psychological phenomena are preceded by mind, have mind as their leader, they are mind-made. If one speaks or acts with an evil mind, suffering follows that one as the wheel follows the ox...If one speaks or acts with an a pure mind happiness follows one  as does a shadow'(Dhp.1,2). 

(2)  Another misunderstanding is that everything that happens to us is the result of our past kamma. The Buddha said that the belief that everything a person experiences is due to their past kamma (pubbekatahetu) is a false and pernicious view leading to fatalism (A.I,173). In fact, Buddhism recognized at least five broad causes of why things happen, of which kamma is only one, the others being the operation of natural laws (dhamm niyàma), biological laws (bãja niyàma), physical laws (utuniyàma) and psychological laws (cittaniyàma, As.854).

(3) Kamma is sometimes seen in simplistic and polarized terms; i.e. it is either good or bad, its results are either positive of or negative, etc. The Buddha was a good enough psychologist to know that human consciousness and motives are often much more complex and nuanced than this and thus will have much more nuanced results. He spoke of kammic consequences that are `neither unpleasant nor pleasant' (adukkha§asukkha§), that is to say, which are the effect of actions that are ethical neutral. At other times he mentions action that `ethically mixed' (vãtimissà dhamma, M.I,318).  

(4)  It is sometimes claimed that we can never escape from the consequences of our past actions. If this were true then we would be completely determined by our past and be unable to change and attain enlightenment (A.I,249). What Buddhism does teach is that several strong intentional good actions may very well modify or even cancel out a bad action and vice versa (Dhp.173). Thus it is correct to say that we are conditioned by our kamma rather than determined by it. (5) Our experiences in the present life are due to what we did in our last life and what we do now will have an effect in the future life. Contrary to this idea the Buddha said: `The result of kamma, I say, is threefold; that to be experienced in this life, or in the next rebirth, or on some subsequent occasion' (A.III,415). It is likely that many of our actions have a result immediately or soon after we have done them, i.e. in the present life

(6). The fourth common misunderstanding is what might be called `kammic naivety', i.e. if you kick a monk in this life you will be reborn with only one leg in your next life, if you swear in this life you will have bad breath in the next life, or if you are generous in this life, you will be rich in your next life. This, of course, is rather silly. Because kamma is primarily psychological (i.e. intention), its manifestation is primarily psychological. It only affects our physical form and circumstances to the degree that the mind can have an influence on the physical, as, for example, when prolonged worry can cause or aggravate physical illness. The main effect kamma has upon us is how we feel (happy, neutral or unhappy) and which realm we will be reborn into. See Determinism and Knowledges, the Three.