Tuesday evening, May 25th, begins the two day holiday of Shavuot (or Shavuos in the Ashkenazic pronunciation).
It is the anniversary and celebration of the giving of the Torah on Mt. Sinai to the Jewish people 3,316 years ago. It is a time of rededication and commitment to learning Torah.
For lots more about Shavuot, go to http://www.aish.com/holidays/shavuot/default.asp