Lag ba’Omer is a minor Jewish holiday celebrated with bonfires and an occasion for weddings and cutting children’s hair. It happens approximately one month after Passover, and the name means the 33rd day of the of the Omer count, on the 18th day of the Jewish month of Iyar, which is about the midpoint in time between Passover and Shavuot.
Lag ba’Omer, according to tradition, was the day on which the plague that killed 24,000 of Rabbi Akiva’s disciples stopped (Yebamoth, 62:72). For this reason it is customary to cease mourning customs of the Omer period, which include prohibition of marriages, cutting hair, and public expressions of joy such as singing and dancing. Some traditions hold that the period of mourning ends at Lag ba’Omer and others end it three days before the holiday of Shavuot.