A Jewish holiday.

Date

The holiday's name literally translates as the 33rd of Omer (LaG meaning "33" in Gematry).

The Omer count begins on the 2nd day of Passover, and Lag BaOmer is held on the 33rd day of that count. Just like other Jewish holidays, the exact date of the event varies according to the Jewish Calendar.

Customs

Most Jewish kids, teenagers and adults, religious or not, go out to set up a bonfire. The event itself does not involve any religious rituals but mostly regular camp-fire socializing, baking hotdogs / potatoes and staying till dawn.

When you're little, your parents would take care of setting it up, watch you closely and send you to bed at 12PM - 1AM tops. From a certain age, when your parents can trust you enough, you can go out with your friends and set up your own independent fire, which involves:

  • collecting wood to get a respectable fire, either from a nearby forest or a nearby construction yard :)
  • shopping for snacks, marshmallows and meats you'd try to fry
and getting an opportunity to do your teenager "I'm a big boy / girl already" declaration.

Religious traditions

Secular people would simply rejoice by the bonfire; some religious people would participate in traditional celebrations (known as "hilula") on Mt. Meron, where Rabbi Shimon Bar Yochai was buried.

History

The custom does not derive from the bible and remains merely as a tradition. According to the tradition, during the Omer count, 24 thousands of Rabbi Akiva's students died from an epidemic, which only suspended on the 33th day. Also, Rav Shimon Bar Yochai, one of Rabbi Akiva's later (post-epidemic) students and the author of "The Zohar" book is said to have passed away on Lag BaOmer.