The period of the Omer is the period of time between the second day of Passover and Shavuot, essentially the time from the barley harvest to the wheat harvest. It's traditionally a period of semi-mourning. On Lag B'Omer, the 33rd day of this period, mourning rituals are abandoned and are replaced with great joy. There are multiple stories for why this date is special. On story claims that a plague killed thousands of students of Rabbi Akiva, a Talmudic scholar. Lag B'Omer was the day on which the plague ceased. Another story claims that Lag BaOmer is the yahrzeit of one of Rabbi Akiva's most famous students, Rabbi Shimon bar Yochai, who is said to have authored the mystical writings of the Zohar, the text of Kabbalah. Rabbi bar Yochai was said to have been so saintly that no rainbows appeared during his entire lifetime.
Lag BaOmer is a day of wedding celebrations and other simchas in the middle of a period of semi-mourning. Many Observant Jews do not cut their hair during the Omer. Boys, at the age of 3, often have their first haircut on Lag BaOmer, with much festivity surrounding the event.
Lag BaOmer celebrations are generally outdoor adventures, especially bonfires. In Israel, people go outside to share a picnic and enjoy the day, and school children celebrate with a field day. The bonfires symbolize the light of Torah.
As a holiday sometimes considered a day in celebration of scholars in general, study and teaching are also popular.
MODERN LAG B'OMER
We can honor the holiday and rejoice on Lag BaOmer in many ways. Perhaps you'll want take time to study a new Jewish text, learn a new ritual you can bring into the rhythm of your days, find a new idea that brings meaning to your life. Have a picnic with family and friends, and take time to appreciate all that surrounds you in the world. Build a bonfire or campfire and meditate on the meaning of the Torah as a light. Get a haircut, especially a child's first haircut. Donate your hair to Locks of Love or another charity that takes hair donations. Learn to shoot a bow and arrow or encourage your kids to play with a bow and arrow play set (representative of the "bow" in Rabbi bar Yochai's "rainbows").
Lag BaOmer falls 33 days after Passover, usually in May or June. An omer is an ancient Hebrew measure of grain. Biblical law forbade any use of the new barley crop until after an omer was brought as an offering to the Temple in Jerusalem. The Book of Leviticus (23:15-16) also commanded: "And from the day on which you bring the offering…you shall count off seven weeks. They must be complete." This commandment led to the practice of the Sefirat Ha'omer, or the 49 days of the "Counting of the Omer,” which begins on the second day of Passover and ends on Shavuot. Lag BaOmer is a shorthand way of saying “the 33rd day of the Omer."
Learn more about Lag B'Omer at reformjudaism.org/lag-baomer, including a history, customs, a Lag B'Omer social justice guide, and information on donating hair from haircuts.