The Persian calendar, also known as the Solar Hijri calendar, is a solar calendar used in Iran and Afghanistan. It consists of 12 months, with the first month, Farvardin, beginning on the vernal equinox, marking the start of spring. The calendar is based on the Earth's revolutions around the Sun, making it highly accurate. Each month in the Persian calendar has either 29 or 30 days, totaling 365 days in a common year and 366 days in a leap year. The calendar is widely used for civil purposes and is important for cultural and religious events in Iranian society.