Under Jewish law, children are not required to observe the commandments, though they are certainly encouraged and taught to do so. But upon turning 13, a boy is considered an adult under the law and is expected to obey all the commandments from then on. He has become a Bar Mitzvah, or "Son of the Commandments." Similarly, a girl becomes a Bat Mitzvah, "daughter of the commandment," upon turning 12.

A Jewish youth automatically becomes a Bar or Bat Mitzvah upon reaching the appropriate age. The accompanying ceremonies are not necessary to attain this status, and they are not mentioned in the Torah or Talmud. They are actually a relatively recent invention, especially the elaborate nature of the celebration.

In its earliest observance, the rite of passage was marked by a boy's first reciting of the aliyah (benediction over the Torah reading), at the first Sabbath service after the 13th birthday. These duties have gradually increased over the years, and may now include reciting the haftarah (selection from the Prophets), reading the entire weekly Torah portion, leading part of the service, or leading prayers.

It is also customary for the youth to make a short speech, which usually begins with the words, "Today I have become a man [or woman]." The father then says a blessing, thanking God for removing from him the burden of responsibility for his child 's sins. This ceremony is usually followed by a reception, which can be as elaborate as a wedding reception.