Magha Purnima, the full moon coming in the month of Magha is called Magha Purnima. Magh month ends on the day of Magha Purnima. This full moon falls during the months of January and February. During the time period of Magha month, the auspicious Kumbh Mela which is held every twelve years. Magha Purnima is considered an auspicious day in North India and thousands of people take a holy dip in the Ganges River on this day.
Thousands of people come to Haridwar and Prayagraj on the full moon day of Magh month to take a holy bath in the river Ganges. Even though it is winter, people take bath in the holy water of Maa Ganga. Bathing in Maa Ganga destroys all sins, hence the importance of bathing in the Ganges becomes even more special on the full moon day. Apart from Haridwar and Prayagraj, other major pilgrimage places like Nashik, Ujjain and Varanasi are holy bath.
If a person cannot go to these pilgrimage places, then before sunrise on this day, he can take a bath with the water of a river, pond, well, etc. Or one can also take bath at home by mixing Ganga water in the bathing water before sunrise. After this Lord Vishnu is worshipped. After the worship is over, after feeding the Brahmins, they send them away by giving donations.
In the month of Magh, the last day of taking a Triveni bath in Prayag is the full moon day of Magh. Yagya, penance and charity have special significance on this day. One should worship Lord Vishnu after retiring from bath etc. You can also perform Shradh for ancestors. One should donate food, clothes, sesame seeds, blankets, jaggery, cotton, ghee, laddus, fruits, grains, patten etc. to the poor.