What are the "defilements"? Simple question, but I would like to know- what are the defilements, according to Theravada Buddhism? I keep hearing this term and would like to find out what it means, according to the original teachings of the Buddha. Thank you
In simple words, defilements are like little clouds that descend on the head -- and when you look around through one of them, you see everything in a different color or blurry or distorted.

That's what they are, they are glitches that affect your interpretation and evaluation. The problem with defilements is that subjectively they are indistinguishable from reality, it just looks like that's the way the external object actually is -- not a cloud over your head. Or you may get really angry with someone and yell at them, thinking your anger is justified - but it really just a defilement, a temporary madness.

In the original Buddha's teaching, as recorded in Pali Canon, the major types of defilements are:


lobha -- usually translated as desire or greed -- that's the defilement that suddenly makes some things appear very likable.
dosa -- usually translated as anger or hatred -- that's the defilement that makes some things appear very wrong.
and moha -- usually translated as ignorance or delusion -- that's the defilement that makes you confused about what's what.


The traditional metaphor is that these three are like the three base paints that mix in various proportions to create the innumerable variety of defilements observed in real life.