In every month there is a Shivaratri on the Chaturdashi Tithi in Krishna Paksha, which is observed as Masik Shivaratri or Masa Shivaratri. Firm devotees of Lord Shiva observe fast and worship Shiva Linga on all these 12 Shivaratri days of the year.
Shivaratri, which is observed in Shravana month, is known as Sawan Shivaratri or Shravana Shivratri. The entire Shravana month is devoted to perform Shiva Puja and hence Shivaratri in Sawan month is regarded as highly auspicious. However, Maha Shivaratri, which is the most significant Shivaratri, falls in February or March, which corresponds to Phalguna month as per North Indian calendar.
The famous Shiva temples in North India, like Kashi Vishwanath and Badrinath Dham, organize special Pujas and Shiva Darshan in Sawan month. In Sawan month, thousands of Shiva devotees visit Shiva temples and perform Gangajal Abhishekam.
North Indian states like Uttarakhand, Rajasthan, Uttar Pradesh, Madhya Pradesh, Punjab, Himachal Pradesh and Bihar follow Purnimant Lunar Calendar. Sawan Shivaratri is more popular in these states. Sawan Shivaratri corresponds to Ashadha Shivaratri in Andhra Pradesh, Goa, Maharashtra, Karnataka, Gujarat and Tamil Nadu where Amavasyant Lunar Calendar is followed.
Vrat Vidhi / Vratam Procedure:
One day before Shivaratri, usually on Trayodashi, devotees should observe fast and eat only one time. On Shivaratri day, devotees perform morning rituals and take Sankalp to observe full day fast without taking any food for the entire day. While observing Sankalp, the self-determined devotees pray to Lord Shiva for his blessings to finish the fast without any problems.
On Shivaratri day, devotees should take a second bath in the evening and should perform Shiva Puja in the night. Next day morning, devotees break the fast after taking bath. The right time to break the fast is between sunrise and before the end of Chaturdashi Tithi, which will give maximum benefit of the Vrat. There is another contradictory opinion that devotees should break the fast only when Chaturdashi Tithi ends. But it is believed that both Shiva Puja and breaking the fast should be done when Chaturdashi Tithi prevails.
Hariyali Amavasya is another auspicious day in Sawan month, which is observed one or two days after Sawan Shivaratri day.