It is recounted in the book of Shemot that after breaking the first Tablets of the Law because of the people's grave sin of idolatry regarding the golden calf, Moses returned to pray to the Lord for forty days and forty nights.
Before climbing to the top of Mount Sinai, he carved new tables, so that G-d could write the Ten Commandments once more with His own hand.
The day he climbed the mountain was the first of the month of Elul and, before ascending, he urged the people to behave in a manner worthy of what was to be the greatest gift the Lord could bestow upon them. To ensure that the people would not stray and commit further grave sins, Moses gave orders for the shofar to be sounded throughout the camp for all the days he would be on Mount Sinai.
The day he communicated divine forgiveness to the people was the 10th of the month of Tishri - Yom Kippur; on that day God forgave the people by granting them the Tablets of the Law once again.
For this reason, from Rosh Chodesh Elul until the eve of Kippur, every night, excluding Shabbat and the nights on which Rosh Hashanah falls, selichot are recited, the prayers in which we entreat the Lord to forgive our sins, just as Moses did at the time when our fathers were in the desert.
Tomorrow evening marks the beginning of Rosh Chodesh Elul, which lasts until Sunday evening. Since the first day falls on Shabbat, the shofar is blown only on the second day - Sunday.
A very important month begins: it is the last month of the year, the one preceding Rosh Hashanah, that day called Yom ha-Din - Day of Judgement.
The month of Elul is also an important time for us Jews. According to the Masters of Kabbalah it is considered the month in which "the King descends into the field", meaning that the Lord G-d is closer to us and is also more willing to listen to our prayers. Therefore, they suggest increasing supplications and prayers to Him, taking advantage of His particular closeness and readiness.
The word ELUL is interpreted by some masters as the initials of a famous verse from the Song of Songs which reads:
"Ani L'dodi V'dodi Li - I am my beloved's and my beloved is mine", paraphrasing the "beloved" as the Lord G-d and the beloved as the Jewish People.
Taking advantage of the night as a time when everyone else is asleep, the Jewish people meet the Lord during the recitation of selichot to express all their love for Him.