The Counting of the Omer is a commandment in Judaism of counting the days that pass between Pesach (Passover) and Shavuot (the Feast of Weeks). This mitzvah (commandment) derives from a commandment in the Torah to count 49 days beginning from the day on which the Omer, a sacrifice containing an omer-measure of barley, was offered in the Temple in Jerusalem, up until the day before an offering of wheat was brought to the Temple on Shavuot. The Counting of the Omer begins on the second day of Passover (the 16th day of Nisan) for Rabbinic Jews (Orthodox, Conservative, Reform), and after the weekly Shabbat during Passover for Karaite Jews, and ends the day before the holiday of Shavuot, which is the 'fiftieth day'. This image depicts an Omer calendar for 1904 produced by Baruch Zvi Ring with ink, paint, pencil, and watercolor on cut-out paper. It is in the collection of the Jewish Museum in New York.Artwork credit: Baruch Zvi Ring