You will often hear reference to the three poisons in Buddhism, What are they referring to exactly when they talk about the three poisons?
Greed (lobha) – mindfulness transforms this into Faith
Aversion/hatred (dosa) – mindfulness transforms this into discriminating Wisdom
Delusion (moha) – mindfulness transforms this into Equanimity
Ven. Bhikkhu Bodhi treats these poisons/kilesas on a deeper level in his book The Noble Eightfold Path, p. 8, 80-81:
The most basic defilements are the triad of greed, aversion, and delusion.
Greed (lobha) is self-centered desire: the desire for pleasure and possessions, the drive for survival, the urge to bolster the sense of ego with power, status, and prestige.
Aversion (dosa) signifies the response of negation, expressed as rejection, irritation, condemnation, hatred, enmity, anger, and violence.
Delusion (moha) means mental darkness: the thick coat of insensitivity which blocks out clear understanding.
From these three roots emerge the various other defilements — conceit, jealousy, ambition, lethargy, arrogance, and the rest — and from all these defilements together, the roots and the branches, comes dukkha in its diverse forms: as pain and sorrow, as fear and discontent, as the aimless drifting through the round of birth and death. To gain freedom from suffering, therefore, we have to eliminate the defilements. But the work of removing the defilements has to proceed in a methodical way. It cannot be accomplished simply by an act of will, by wanting them to go away. The work must be guided by investigation. We have to find out what the defilements depend upon and then see how it lies within our power to remove their support.
And also very importantly how to deal with the defilements:
"...the root defilements is conditioned by a particular kind of feeling: greed by pleasant feeling, aversion by painful feeling, delusion by neutral feeling. But the link between feelings and the defilements is not a necessary one. Pleasure does not always have to lead to greed, pain to aversion, neutral feeling to delusion. The tie between them can be snapped, and one essential means for snapping it is mindfulness. Feeling will stir up a defilement only when it is not noticed, when it is indulged rather than observed. By turning it into an object of observation, mindfulness defuses the feeling so that it cannot provoke an unwholesome response..."
The three poisons (Sanskrit: triviṣa; Tibetan: dug gsum) or the three unwholesome roots (Sanskrit: akuśala-mūla; Pāli: akusala-mūla), in Buddhism, refer to the three root kleshas of ignorance, attachment, and aversion. These three poisons are considered to be the cause of suffering (Sanskrit: dukkha).
They are commonly circumvented by contemplating on the three characteristics or marks of all existence - anicca, anatta and dukkha. See this talk in the Burmese vipassana tradition.
See also, kleshas
Curiously on page 66 (page 87 of the PDF) of How Buddhism Began – The conditioned genesis of the early teachings, the author suggests that the "three poisons" are the result of people misinterpreting (i.e. taking literally) a metaphor that the Buddha used.
I don't know (maybe didn't understand) but maybe that's reflected in the comments below this answer, where Andrei (whose tradition is I think Tibetan Buddhism, compared with yuttadhammo's Theravada) ascribes more importance to three poisons e.g. by including aversion as one of the causes of suffering in the second noble truth (that's maybe also visible in Buddho's answer to this question).