It is customary to observe the day of Lag Ba’omer with a degree of festivity. Different reasons are given by the Poskim for the celebration on Lag Ba’omer. Most obviously, Lag Ba’omer is the day when, according to one opinion, the plague that killed Rabbi Akiba’s students came to an end. Additionally, Lag Ba’omer is the day when Rabbi Shimon Bar Yohai died, and just before his death he instructed his disciple, Rabbi Abba, to write the Zohar which included many profound insights that had until then been kept secret. Lag Ba’omer is thus observed as a joyous occasion, because it was then when the great wisdom of the Zohar was revealed.
Additionally, after the death of Rabbi Akiba’s students, he began teaching five new, outstanding students – one of whom was Rabbi Shimon Bar Yohai – through whom the Torah tradition was kept alive. It was on Lag Ba’omer when he conferred upon them Semicha, and it is thus an occasion for festivity. Furthermore, it was on this day when the Manna began to fall for Beneh Yisrael in the wilderness, and Lag Ba’omer is thus a day of Parnasa (sustenance) and a time for celebration.
Many have the custom to visit the gravesite of Rabbi Shimon Bar Yohai on Mount Meron in Northern Israel on Lag Ba’omer, and pray and celebrate at the site. Kohanim are forbidden from entering the building in which the gravesite is situated. Some have the custom (which is mentioned in Sha’ar Ha’misvot) not to visit Rabbi Shimon Bar Yohai’s gravesite alone, and to instead ensure to go there with at least one other person. There is also a custom observed by some that women do not visit the site while in a state of Nidda. It is customary on Lag Ba’omer to light candles in memory of Rabbi Shimon Bar Yohai and in memory of his son, Rabbi Elazar. The Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909), in his work Torah Lishmah (223), writes that according to Kabbalistic teaching, one candle should not be lit for two Sadikim; a separate candle should be lit for each righteous person. Therefore, one should ensure to light one candle for Rabbi Shimon and another for Rabbi Elazar.
Tahanunim are omitted from the prayer service on Lag Ba’omer. Our custom is to also omit Tahanunim during Minha on the day before Lag Ba’omer.
The night after Lag Ba’omer has the same status as Mosa’eh Shabbat with regard to the recitation of Keri’at Shema Al Ha’mita (the bedtime Shema). Thus, if one recites Keri’at Shema Al Ha’mita before Hasot (midnight as defined by Halacha), then he should omit the solemn "Ana" section, as that part of the night is still associated with the festive day of Lag Ba’omer. If, however, one recites the bedtime Shema after Hasot, then he includes the "Ana" prayer.
According to Sephardic custom, eulogies are given and the "Siduk Ha’din" recitation is said on Lag Ba’omer, whereas Ashkenazim follow the practice not to give eulogies or recite "Siduk Ha’din" on Lag Ba’omer.