Coming seven weeks after Passover, Shavuot, the "Festival of Weeks," commemorates when God gave the Torah to the Jewish people at Mount Sinai. The exodus from Egypt, for all its drama, was only a means to an end; God didn't take the Jews out "with a strong hand" just so they could go to summer camp in the desert. They would serve him. But they would need the instruction manual.
This holiday begins on the 6th of Sivan, the date God gave the Torah. Shavuot doesn't get as much press as other Jewish holidays, but it's just as important. Without the Torah, there is no framework for Judaism beyond mere belief. Most Jewish philosophers believe that Judaism is based on action, not just words and thoughts.
The name "Shavuot" stems from the counting of the Omer, the seven weeks between Passover and Shavuot. On this holiday Jews read the Book of Ruth, which tells of a convert woman who remained dedicated to her mother-in-law even after Ruth's husband dies. Her devotion to her family and Judaism were significant enough that King David descended from her bloodline.
Shavuot is similar to the other two major festivals, Passover and Sukkot, in that it has Shabbat-like restrictions against work, but is different in that it's only two days long, one in Israel.
For a variety of reasons, it's also when Jews eat cheesecake. Main reason? It tastes good.
