Introduction to Tractate Keritot
Keritot (sometimes pronounced Keritut) is the plural of karet, which is a punishment found quite frequently in the Torah for various transgressions (Leviticus 17:4, 9; Exodus 30:33, 38; Genesis 17:14; Numbers 15:31 and many others). Karet is variously translated as excommunication or extirpation or other similar term. The rabbis interpret this punishment to be one that is meted out by God and not by a human court. One interpretation is that the person will die an early death. Another interpretation is that the punishment is meted out on the person in world to come.
Despite the fact that the title of the tractate is Keritot, the subject of most of the tractate is those who are obligated to bring a hatat (sin-offering) an asham, and especially an asham talui. The asham talui is referred to in Leviticus 5:17-19:
17And when a person, without knowing it, sins in regard to any of the Lord’s commandments about things not to be done, and then realizes his guilt, he shall be subject to punishment. 18 He shall bring to the priest a ram without blemish from the flock, or the equivalent, as a guilt offering. The priest shall make expiation on his behalf for the error that he committed unwittingly, and he shall be forgiven. 19 It is a guilt offering; he has incurred guilt before the Lord.
The asham (guilt offering) referred to in this passage is interpreted by the rabbis as being brought by one who does not know if he committed a son or not. For instance, he ate a piece of fat and he doesnt know whether it was helev, which is prohibited or shuman, which is permitted. If afterwards it turns out that it was helev, then he must bring a hatat. One only brings an asham talui or a hatat for a sin which one would be liable for karet if it was done intentionally. This connection between the hatat and the asham talui and karet is why our tractate begins with the subject of karet.
As always, good luck in learning Keritot!