Teshuvah -- frequently translated as repentance -- actually means returning. Judaism emphasizes that our essential nature -- the divine spark of the soul -- is good.
True repentance is best achieved not through harsh self- condemnation, but through the realization that our deepest desire is to do good, in accordance with the will of G-d.
Our sages explain that on Rosh Hashana, we all stand in judgment before G-d -- "like a flock of 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.
Through repentance, prayer, and charity, we can sweeten the decree, and merit G-d's blessings for health, wellbeing, and prosperity for the coming year.
Another beautiful custom for this day is that of parents blessing their children with the Priestly Benediction: "May G-d bless you and guard you... May G-d shine His countenance upon you and be gracious to you... May G-d turn His face toward you, and grant you peace.
Yom Kippur atones for sins against G-d, but not for wrongdoings between man and man. It is therefore important, on the day before Yom Kippur, to apologize and seek forgiveness from friends, relatives, and acquaintances, to heal any ill feelings which may have arisen.
For on Yom Kippur we receive what is perhaps G-d's most sublime gift: His forgiveness. When one person forgives another, it is because of a deep sense of friendship and love that overrides the effect of whatever wrong was done. Similarly, G-d's forgiveness is an expression of His eternal, unconditional love.
Though we may have transgressed His will, our essence - our soul remains G-dly, and pure. Yom Kippur is the one day each year when G-d reveals most clearly that our essence and His essence are one. Moreover, on the level of the soul, the Jewish people are all truly equal and indivisible.
The more fully we demonstrate our essential unity by acting with love and friendship amongst ourselves, the more fully G-d's love will be revealed to us.