In
Judaism, this is the second and last
rite of passage, occurring some number of years (depending on the
synagogue you attend) after the grand
bar mitzvah. In my
synagogue (
temple, for you
goys), it occurs at 17.
I am pretty sure that this is a relatively modern invention.
It is basically a graduation from the studies of youth, otherwise known as hebrew school or sunday school. Those reaching confirmation have usually continued their judaic education of their own volition, and thus make up a significantly smaller group than that of the bar mitzvah class.