Fast on Monday is observed to please Lord Shiva and Goddess Parvati. According to the scriptures, fasting period of this Vrat is between sunrise and sunset. As food is taken at night, the fast is also called as Nakta Vrata. Monday fasting is considered auspicious if started from first Monday of Shukla Paksha or Shravan month. Proedure of this fast is similar to the Vrata observed in Shravan Maas. In this month, specially Shiva Lingam is worshipped.

Fast on Monday is observed to please Lord Shiva and Goddess Parvati. According to the scriptures, fasting period of this Vrat is between sunrise and sunset. As food is taken at night, the fast is also called as Nakta Vrata. Monday fasting is considered auspicious if started from first Monday of Shukla Paksha or Shravan month. Proedure of this fast is similar to the Vrata observed in Shravan Maas. In this month, specially Shiva Lingam is worshipped.
If a person is not able to start this fast from Shravan month, then he can start it on the first Monday of Shukal Paksha in the following months ~ Chaitra Masa, Baishak Masa, Kartik month or the Margshirsh month. Out of these, Shravan Masa is considered the most auspicious time. This month is most dear to Lord Shiva. All sins of a person are destroyed, if he starts the Monday fasting from Sharavan month. This fast was observed first by Goddess Parvati in order to get Lord Shiva as her husband. by the auspiciousness of this fast she got Lord Shiva in form of her husband.
The 16 Monday fasting (Solah Somwar) is considered the most favorable out of all the fast of Lord Shiva. This fast is kept mostly by unmarried girls for a happy and peaceful life. Monday fast is kept by men for getting child, wealth and prestige. The fast is started in any of the auspicious month as stated above. This fast should be kept for 16 Mondays with full faith and confidence. The person doing Upvas should get up early in the morning and bath with water containing black Til. Worship Shiva idol or photo and chant the mantra Om Namah Shivaya". The resolution of this fast should be taken infront of Lord Shiva and Goddess Parvati with white flowers, sandalwood, rice, Panchamrit, fruits, holy water. After taking the resolution and doing Puja, Vrat Katha should be heard. Then, the Aarti should be performed and Prasadam is to be distributed. Avoid using salt in meal. While the Udhyapan (conclusion) of fast, white things should be donated, like rice, white clothes, sweets, milk, curd, silver etc. This fast is also done for mental peace. After the full day fasting, person should have a vision of Lord Shiva in the Shiva temple. At the time of sunset, food materials made of milk should be used in offerings. Lord Bholenath should be offered the Bhog, and after worshipping with incense stick, deep, the Moon God is given the Ardhya. After the completion of Solah Somvar Vrat, on the day of Udhyapan, Brahmans and children should be given Kheer, Puri, sweets etc and donations as per the capacity of an individual. On sunset, worshipping of Lord Shiva in Pradosh Kal is considered the most favourable.