Vrat means fasting. On the Vrat day, there are certain restrictions on the natives observing the fast. Each Vrat guideline can differ a little. The timing can vary. In some fasts, one vegetarian meal in the Vrat date is allowed; at times certain Vrat food items without salt are acceptable by the norms. Normally the consumption of fruits and milk are permitted. There are different kinds of Vrat for different occasions-days-dates, different purposes and for different results. It is generally also considered good for physical and mental health, and wellbeing. Many modern-day medical fraternity groups acknowledge and endorse this.
There are typically two Pradosh Vrats in a Gregorian and Hindu calendar month. The Pradosh Vrat date-timings are based on the moon-lunar cycle, fortnights of the Shukla Paksha and the Krishna Paksha. Shukla Paksha is the waxing-rising phase of the moon, and Krishna Paksha is the waning-decreasing phase of the moon. The dates are best reflected in a Hindu lunar calendar. Pradosh Vrat falls once in each of these two phases on Trayodashi. Trayodasha, a Sanskrit word, means the number 13. Trayodashi means the 13th day; in this context, the 13th day of the lunar-moon phase.
Pradosh, a Sanskrit word means evening, dark, dusk or nightfall. Therefore, the Puja, prayer ceremony is conducted in the evening of the Pradosh Vrat; normally any time between 5:30 pm to 9:30 pm, depending on the region, sunset, time zone etc.
Pradosh Vrat is observed by devotees in the worship of and in dedication to deity Lord Shiva and his consort Goddess Parvati. Lord Shiva is regarded as in the top three of the Hindu deities. Natives-devotees seek the blessings of Lord Shiva on this day. Lord Shiva helps in protecting the natives, destroying the evil, seeking forgiveness for any sins, for good health, for a happy family life, to achieve Moksha after death etc. Lord Shiva is also known as the God of Spirituality, meditation, mental peace, Yoga, arts etc.
Devotees normally bathe about an hour before the sunset on the day of Pradosh Vrat, especially in preparation for the prayers. They clean their homes, surroundings etc. Then, as per the evening-dusk scheduled Puja timing, they prepare to perform the worship.
A Mantra for Lord Shiva is
Om Namah Shivaaya
ॐ नम: शिवाय