Lag B’Omer is a minor holiday celebrated on the 33rd day of the omer, a Hebrew word meaning unit. Counting the omer spans a 49-day period, beginning on the second day of Passover and ending on Shavuot. This ancient custom, linking the Exodus from Egypt with the giving of the Torah at Mount Sinai, reminds the Jewish people that redemption from slavery wasn't complete until they received the Torah.
Although the omer is a time of mourning, when celebratory acts such as marriage, haircuts and concerts are forbidden, the prohibitions are lifted on Lag B'Omer. Couples wed, children play outdoors and people often gather for large bonfires, which represent the light of the Torah.