According to the Gregorian Calendar, the full day (daytime and night) starts at 12.00 o’clock midnight whereas in the Solar one, it starts from the sunrise. In the case of Lunar calendar, which follows the course of the moon, the Lunar day or the ‘tithi’ is from one moon-rise to the next one. The lunar month has 30 days and going by the waning and waxing of the moon, the month is divided into two fortnights called Krishna Paksha (Bahula is another name) and Shukla Paksha (Shuddha). For the sake of better understanding Krishna Paksha is often called in English, Dark Fortnight and Shukla, Bright Fortnight, or the Bright Half (half a month). The Bright Half consists of waxing of the moon whereas the Dark Half, waning of the moon.

Lunar Months :
The Lunar Month starts from the first day of waxing and each tithi for 14 days is literally called First day, Second day, Third day etc and on the 15th day it will be Poornima or the Full Moon Day when one can behold the full circle of the moon rising exactly after the sunset and setting when the sun is going to rise, the next day. From the 16th day, the First day of the Dark Half starts again with the same name of the tithi and ends up with Amavasya, the night long darkness. Lunar calendar too has twelve months. They bear the name of the constellation of the stars with which the moon rises on the full moon day. For example, in the first month of Chaitra, the moon will rise with the Chitra star and Vaishaka, with Vishakha star. These twelve months make a year or Samvatsara and, the Indian Calendar believes in a cycle of 60 years and therefore each of these 60 years will have a name, the first year of the cycle is Prabhava and the last one is Kshaya. For the year 2,000 AD we have from this Chaitra the 14th Samvatsara called Vikram. The Panchang gives the names of all the 60 years every time for a beginner to know. The twelve lunar months are as follows: 1. Chaitra (March-April), 2. Vaishakha (April-May), 3. Jyestha (May-June), 4. Ashadha (June-July), 5. Shravana (July-August), 6. Bhadrapada (Aug.-Sept), 7. Ashwij (Sept.-Oct.), 8. Kartik (Oct.-Nov.), 9. Margashirsha (Agrahayana)(Nov.-Dec.), 10. (Pushya/Pausa) (Dec.-Jan), 11. Magha (Jan.-Feb) and 12. Phalgun (Feb.-March).  
The Lunar Calendar does not want to go alone and wants to catch up with the movement of the sun and stars and so to coquilles after every three years adds a month called Adhik Mas or an additional month which can be called a leap month. As an exception there will be a Kshaya Mas or a deduction by a month also. But this will be a very rare occasion, and had happened in 1985.  

The New Year :
The New Year begins with the First day of Chaitra month called Yugadi or Gudipadva. It is stated that it is the first day of creation of this universe by Lord Brahma, the creator. The Hindu year goes by Shalivahana Shaka or the year of Shalivahana, the great King who ruled over this country twenty centuries ago. The current year is 1922, which suggests the year of coronation of Shalivahana. So from the point of view of Indian Calendar, we have 78 years to go to reach the third millennium.

Going back to our study of months and year, the year is divided into two halves, depending on the course of the sun called the Uttarayana and Dakshinayana which literally mean, Northern Course and Southern Course of the sun in the zodiac. Uttarayana is supposed to be more auspicious than the Dakshina. Each  ‘ayana’ has three seasons as under the Lunar Calendar, we have six seasons in a year. 
They are: 1. Vasanta (spring: Chaitra & Vaishakha) 2. Grishma (summer: Jyestha & Ashadha), 3. Varsha (rains: Shravan & Bhadrapada), 4. Sharad (autumn: Ashvij & Kartik), 5 Hemanta (winter: Margashira & Pushya) and 6. Shishira (cool: Magha & Phalgun). Thus the Lunar calendar starts roughly with April and ends up in March and interestingly the financial year of India corresponds with our lunar calendar. With this preliminary study of Indian calendar we proceed now with the festivals and fasts of GSBs.  

1. Chaitra :
1. The First Day of the Shukla Paksha, New Year’s Day. Lord Brahma on this day created the Universe. How may years ago? Our astrologers, in the Panchang  say 197,29,49,099 years ago. Decades ago people used to buy new clothes sufficient for one full year and in between  except ceremonies like wedding and upanayanams they were not buying  new clothes.  In temples the New Panchang  is ceremoniously released and the Samvatsara Phala  or the predictions for the whole year are read out, rain, sunshine, crops, metals, business position, war or peace, prosperity plenty  or draughts and  earthquakes  and ultimately the political situation also. It is worth going through the predictions. New clothes are  put on. Then in some families there is a system of “kappad vadap” which means dedication of saris and dhotis to the memory of  the departed souls with an offering of food or sweet beaten rice and an arti. The head of the family does it without the assistance of a priest and after food, the dhoti will be put on by him and sari, his wife.  
2. Shukla 9th day: Shri Rama Navami, Lord Rama’s Birthday.
3. Poornima, Shri Hanuman Jayanti.

2. Vaishakha :
1. Shukla 3rd day: Akshaya tritiya-Shri Parashurama Jayanti.
2. Shukla 14th day: Shri Narasimha Jayanti.
3. Full Moon: Koorma Jayanti and Kartika Poornima.

3. Jyestha :
1. Shukla 14th Day: Vatasavitri Vrita.

4. Ashadha :
1. Shukla Ekadasi  Prathama Ekadashi  or Ashadi: Fast and prayers.

5. Shravan :
1. Shukla 5th day: Naga Panchami: Milk is offered to naga carvings in temples and naga bans with arti and prayers to nagas.  
2. Poornima: Rig Upakarma: Change of janwa or the sacred threads. The married will have two janwas and the unmarried will have one with three threads. It is to be put on around the body passing from the left shoulder. The three threads indicate Brahma,Vishnu and Maheshwara according to one version but according to a more meaningful version the three threads signify our indebtedness throughout the life for three great institutions 1. All gods who have granted us all natural resources free, to live on this earth. 2. Our parents who have given us birth and life and first knowledge soon after we were born but before we were sent to school . Here parents include our forefathers also. And 3. Our Sages and Acharyas who have given us the gift of knowledge. The janwa gives us full protection against every evil, this is what the scriptures proclaim. 
3. 8th day of Krishna Paksha: Shri Janmashtami: The Birthday of Lord Krishna. 

6. Bhadrapada :
1. Shukla 3rd day: Gowri Pooja and Vayana Pooja. 
2. Shukla 4th day: Shri Ganesh Chaturthi, Ganapati Pooja. 
3. Shukla 14th day: Shri Anant Chaturdashi. 
 
The entire Krishna Paksha, thereafter is called Mahalaya with Amavasya  at the end called Mahalaya Amavasya. This fortnight is dedicated to pitras or our departed forefathers who re supposed to visit us during this period. Tarpans and shraddhas are offered in memory  of them.

7. Ashwija (Ashwin or Ashwayuja) :
1. The first 9 days of the Shukla Paksha constitute Navaratri with the worship of Mother Goddess Durga and all our Kuladevas where  She is amongst us assuming  different names. 
2. Vijaya Dasami, most of the temples will worship new paddy corn and  distribute to their devotees. New corn is brought home and tied to the pillars, treasury, vessel in which grain is stored etc. invoking plenty and prosperity.  
3. Krishna Paksha 14th day: Naraka Chaturdashi  with traditional oil bath in the early hours of the morning. 
4. Amavasya Day: Gow-pooja, Shri Laxmi Pooja in shops and offices and Bali pooja also.  

8. Kartik :
1. Shukla 11th day: Kartik Ekadashi: Full day fast and night prayers. 
2. Shukla 12th day: Tulsi Pooja. 
3.Poornima: Kartik Poornima: Deepotsava in a good number of temples.  

Fasts :
In lunar calendar, every fortnight has one Ekadashi, and the scriptures ordain that the Ekadashi should be observed by way of fast during daytime and prayers at  nights. And the fast should be broken on Dwadashi Day, i.e. the next day morning. But in the present day context, two Ekadashis, Ashad and Kartik are observed by many religious minded people. But our temples, maths, swamijis and the priests observe all the Ekadashis.