What is Kiddush Levana?

Kiddush Levana, literally "Sanctification of the Moon," is a short prayer service recited each month upon sighting the new moon. It is customary to recite Kiddush Levana together with as many people as possible, but preferably with at least one other person. The prayers may be recited only until the conclusion of the fifteenth day of the Hebrew month after the rebirth of the moon. According to Kabala, they should not be recited before he seventh day after the rebirth of the moon. The prayers should be recited under the open skies, but may not be recited when the moon is covered with clouds. It is preferably to recite Kiddush Levana on Saturday night, while one is still in festive clothing.