Bar mitzvah is Hebrew for “son of commandment.”
When a Jewish boy turns 13, he has all the rights and obligations of a Jewish adult, including the Mitzvot - Commandments of the Torah.
From that date, he will wear tefillin on a daily basis, participate in synagogue services as an adult and take his place in the Jewish community.
Many times we jokingly call a Bar Mitzvah Boy a MAN, since he accepts all adult male mitzvot (commandments) upon turning 13.
This milestone, called a Bar Mitzvah, is often celebrated with a ceremony in the synagogue, tefillin wearing, and parties. The celebrant may lead services, deliver a speech or otherwise demonstrate his newfound status.
The Bar Mitzvah is automatic, whether or not a celebration or special ceremony is held.
But since becoming a Bar Mitzvah is such an important milestone and joyous occasion, we make a point of celebrating together with family and friends.
There are so many different ways to celebrate and they are all fun! Some have a party, some go on a Safari, some have a dinner in a restaurant and some have a Kiddush - small meal on Shabbat in the synagogue.
Since a boy will become Bar Mitzvah only once during his lifetime, we love to commemorate this day with personalized gifts, swag, mementos, and souvenirs!
(adapted from chabad.org)