Rosh Hashana, which literally means the "head of the year", marks the beginning of the Jewish calendar year. Rosh Hashana is colloquially called the "Birthday of the World", for it is said that GOD created the world on this day, the first day of Tishrei. Other traditions say that Rosh Hashana marks the creation of Adam, completing the creation process.
Rosh Hashana begins this year at sunset on September 17 with Erev Rosh Hashana, or Eve of the New Year. On this evening, after services, the traditional blessing "May you be inscribed and sealed for a good year" is exchanged. The Jewish Sages explain that on Rosh Hashana, we all stand in judgment before GOD, "Like a sheep before The Shepherd". If we are worthy, we are inscribed in the "Book of Life". Ten days later, on Yom Kippur, the Book is sealed.
Teshuva, frequently translated as "repentance", actually means "returning". During this period of time, we seek forgiveness from those we have wronged in any way before we appear before GOD and ask His forgiveness. Yeshua also emphasized this concept in Matthew 5:23-24 when He said, "first be reconciled to your brother, and then come and present your offering."
The importance of observing Teshuva is that we not only confess our sinful ways, but that we "return" to the right way, or GOD’s way. In the parable of the Prodigal son, the "wayward" son says, "I will return and go to my Father." In Hosea 14:2,3 the scriptures say, "Return, O’ Israel, to the LORD your GOD, for you have fallen because of your sin. Take words with you (confess) and return to the LORD." In the same way, during Teshuva, we are to confess our shortcomings and return to the ways of GOD.