(An Omer is a Biblical measure of a sheave of barley)
Biblical Sources: Leviticus 23:9-12
"The L-rd spoke to Moses, saying: 'Speak to the children of Israel, and say to them: When you shall enter the Land that I give you, and reap its harvest, you shall bring an Omer from your first harvest to the priest. And he shall wave the Omer before the L-rd, to be accepted for you. On the day after the rest day, (the first day of Passover), the priest shall wave it. On the day you wave the Omer, you shall perform the service of an unblemished lamb as a burnt-offering before the L-rd. Its meal-offering shall be two tenths of an ephah of fine flour mixed with oil, a fire offering to the L-rd, a satisfying aroma; and its libation shall be wine, a quarter-hin. You shall not eat bread or roasted kernels or plump kernels until this very day, until you bring the offering of your G-d; it is an eternal decree for your generations in all your dwelling places.
You shall count for yourselves - from the day after the rest day (Passover), from the day when you bring the Omer of the waving - seven weeks, they shall be complete. Until the morrow of the seventh week you shall count, fifty days; and you shall offer a new meal offering to the L-rd."
On the 16th of Nissan, the day following the first day of Passover, pilgrims and priests alike would gather in the fields outside of Jerusalem, and initiate the barley harvest. The barley was then carried by the priests back to the Holy Temple, where, in the eastern side of the Sanctified Court, (between the altar and the Nikanor Gate leading to the Women's Court), the priests would sift the barley through thirteen sieves, then beat and roast it. The barley kernels were roasted in a specially perforated pan. The pan sat atop a stand that also held a lower pan that would be filled with hot coals. This vessel was called the Abuv. After the barley was roasted, it was beaten into a coarse meal. The pan was then lifted by the priest up out of the Abuv, and, standing before the altar, a second priest would add a measure of frankincense, while a third priest added olive oil, in accordance with the commandment concerning all meal offerings. The priest would then carry the pan of prepared barley to the northeast corner of the altar, where he would "wave the Omer before G-d."
He would then proceed to the southwest corner of the altar, and present the Omer offering there, as was done with almost all meal-offerings. Finally, the priest would ascend to the altar, where he would scoop out a handful of the Omer grain, and drop it into the altar fire. This was followed by the bringing of a single male sheep, as a burnt-offering. From this point on, barley from the new harvest could be consumed by all. The remaining grain that had been brought up to the Holy Temple by the priests would then be eaten by the priests. Meanwhile, the marketplaces of Jerusalem, in anticipation of this moment, were already laden with grain products from the new barley harvest. Anxious Jerusalemites and pilgrims alike would flock to the markets to purchase the barley products.
The offering of the Omer began the forty nine day counting period that leads up to the Shavuot pilgrimage festival. Shavuot, which literally means "weeks," falls out on the fiftieth day following the Omer offering, seven complete weeks having been counted from the conclusion of the first day of Passover - "the day after the rest day."
It is a Biblical commandment - "You shall count for yourselves" - to literally count each day of the Omer out loud. This act of counting is today performed by Jews the world over, each evening at the conclusion of the daily evening prayer service. One must keep track of the days and weeks that have elapsed, until the Festival of Shavuot. In keeping with this commandment, we shall be posting the number of each day's Omer count on the page.
Traditionally, the forty-nine day period of the "counting of the omer" - known in Hebrew as Sefirat Ha-Omer - is seen as a period of intense personal and spiritual growth. If we are sensitive to all the spiritual nuances of these days, these 49 days can be a journey through human personality, presenting us with an opportunity to refine and perfect our emotions and character traits. When the people of Israel left Egypt, they needed a purification period of seven complete weeks before receiving the Torah at Mount Sinai. During this period, Israel ascended through 49 levels of spiritual growth, corresponding to these 49 days. Each day of the sefirah corresponds to a specific area for growth and hopefully, with G-d's help, positive change.