Lag B’Omer is a minor holiday that occurs on the 33rd day of the Omer, the 49-day period between Passover and Shavuot. A break from the semi-mourning of the Omer, key aspects of Lag B’Omer include holding Jewish weddings (it’s the one day during the Omer when Jewish law permits them), lighting bonfires and getting haircuts.

Why We Celebrate
There are a few explanations why we celebrate Lag B’Omer, but none is definitive.

The Omer is a time of semi-mourning, when weddings and other celebrations are forbidden, and as a sign of grief, observant Jews do not cut their hair. Anthropologists say that many peoples have similar periods of restraint in the early spring to symbolize their concerns about the growth of their crops. But the most often cited explanation for the Jewish practice comes from the Talmud, which tells us that during this season a plague killed thousands of Rabbi Akiva‘s students because they did not treat one another respectfully. The mourning behavior is presumably in memory of those students and their severe punishment.

According to a medieval tradition, the plague ceased on Lag Ba’Omer, the 33rd day of the Omer. (The Hebrew letters lamed and gimel which make up the acronym “Lag” have the combined numerical value of 33.) As a result, Lag Ba’Omer became a happy day, interrupting the sad­ness of the Omer period for 24 hours.