The waning gibbous is a phase of the lunar cycle that occurs after the full moon. During this phase, more than half of the moon's surface is illuminated, but the visible portion gradually decreases each night. The term "waning" indicates that the moon is transitioning from full to new, while "gibbous" refers to its rounded shape. This phase typically lasts about a week, starting right after the full moon. As the days progress, the illuminated part of the moon shrinks, leading to the next phase known as the last quarter. Observing the waning gibbous can help in understanding the lunar cycle and its impact on various natural phenomena.