Vikram Samvat is an ancient calendar system that is still in use in some parts of India, particularly in the northern and western regions. It was established by King Vikramaditya of Ujjain in 57 BCE and is based on the lunar cycle.

The Vikram Samvat calendar is also known as the Hindu calendar or the Indian national calendar. It is used to determine the dates of important Hindu festivals and events, as well as the agricultural and astronomical cycles. The calendar has 12 lunar months, with each month beginning on the day after the full moon and lasting for approximately 29.5 days.

One of the important festivals celebrated according to the Vikram Samvat calendar is Diwali, which falls in the month of Kartik. Other festivals that are celebrated according to this calendar include Holi, Dussehra, and Navratri.

In addition to its religious and cultural significance, the Vikram Samvat calendar also has historical and political significance, as it was used by various Indian kingdoms throughout history. It is still widely used today, particularly in northern and western India, and is an important part of the cultural heritage of the region.