From My Jewish Learning:
Selichot refers to two related types of penitential (forgiveness) prayers. The first are the prayers that are customarily recited daily at early morning services during the month of Elul. This is also the name of the service that takes place late at night on the Saturday preceding Rosh Hashanah and consists of a longer series of these penitential prayers.
A Moving Service
The effect of a Selichot service can be quite moving. The mere gathering together of people at a time when they are usually asleep is impressive. We sense the extraordinary nature of the prayer and turn introspectively within ourselves. The prayers themselves are pleas for mercy. The melodies are sad and full of longing. They form an oratorio expressing the despair that accompanies separation from God and the desire to change and repent. The self‑deprecation contained in the words, which express the feeling of life’s fleetingness, and the burden of vanity that motivates so much of what one does, all cause us to ponder how we can break the cycle of our lives and change ourselves for the better. The possibility of change and of a better life is inherent in these prayers:
“O Lord, hear our voice in the morning; in the morning we set them before You with hopeful expectation. Hear our voice…”
It is always darkest before the dawn. Yet the dawn is not far off, both literally and figuratively.