Lag B’Omer is a Jewish holiday celebrated on the 33rd day of the counting of the omer, which is the 18th day of the Hebrew month of Iyar. There are many explanations for its origin, and ways to commemorate this day. The counting of the omer is the forty-nine-day period between the Jewish holidays of Passover and Shavuot as stated in the Hebrew Bible: Leviticus 23:15–16, and each day is traditionally "counted" out loud during synagogue services.