The Islamic calendar is a lunisolar calendar system that calculates time based primarily on the cycles of the moon. Its fundamental unit of time is the lunar month, which is determined by the synodic cycle of the moon, approximating 29.5 days. Consequently, the calendar year contains approximately 12 lunar months, resulting in a length of roughly 354 days. To account for the discrepancy between the shorter lunar year and the longer tropical solar year—which tracks the seasons—the system incorporates an intercalation mechanism. This addition of extra months, known as the leap month, occurs cyclically over periods of years to synchronize the calendar with the astronomical seasons, thus maintaining a correlation with the solar cycle.