Shavuot, the Jewish Festival of Weeks, is the second of the three major festivals with both historical and agricultural significance. From the second day of Passover to the day before Shavuot is 49 days or 7 full weeks, hence the name of the festival. Agriculturally, it commemorates the time when the first fruits were harvested and brought to the Temple. Historically, it celebrates the giving of the Torah by God at Mount Sinai. It is customary for Jews to stay up the entire first night of Shavuot and study Torah, then pray as early as possible in the morning. It is also customary to eat a dairy meal at least once during Shavuot.
Shavuot runs through May 27.