Shavuot — "Festival of Weeks" — commemorates the giving of the Torah at Mount Sinai. It falls 50 days after Passover, hence the Greek name Pentecost.
Originally an agricultural festival celebrating the wheat harvest and first fruits brought to the Temple. After the Temple's destruction, Shavuot took on its primary identity as the celebration of revelation at Sinai.
All-night Torah study (Tikkun Leil Shavuot). Dairy meals — multiple symbolic explanations: the Torah is compared to milk and honey; meat hadn't yet been kosher-prepared at Sinai. Decorating synagogues and homes with flowers and greenery. Reading the Book of Ruth.
Cheesecake, blintzes, kugel, cheese-filled pastries. Bourekas. In Sephardic communities: cheese-filled boyos.
"Chag Sameach" · "Chag Shavuot Sameach"
1-day public holiday in Israel (2 days in the Diaspora). Major Tikkun Leil Shavuot study sessions at Hebrew University and other venues.