daf bit: K'ritot 2
This tractate begins with a list of 36 transgressions for which the punishment is being cut off (see below). This list includes: sleeping with one's close relatives (e.g. mother), idolatry, having a familiar spirit (!), desecrating Shabbat, eating blood, eating chametz during Pesach, eating or working on Yom Kippur, and transgressing circumcision. The punishment applies if the transgressions are willful; if unintentional, one is liable to bring a sin-offering. (2a)
As I understand it,
the punishment of karet applies when a human court couldn't convict
you (lack of warning in a capital case, not enough witnesses, etc).
I've seen different interpretations of what this means: that God will cut
your life short, or that you are to be exiled (which was often a death sentence),
or that you'll be alienated from God. I asked on Judaism.SE about the relationship between karet offenses
and death-penalty offenses; it looks like there's overlap but neither
is a subset of the other.

no subject