Atharv Sheersh is the part of Atharv Ved. It was written by Atharvaa Rishi who had Ganapati Darshan. It is customary to invoke the name of Ganapati before beginning anything. This Divine experience led him to write this prayer. There is an Upanishad also by this name. The text asserts its own status as an Upanishad in its final line, which reads thus, "Upanishad ends here...". It is the most widely recited Sanskrit text recited among devotees of Ganesh. The entire text is written over to the entrance to the temple hall in the Asht Vinaayak Ganesh shrine at Ranjan Gaaon.

The Ganesh Atharv Sheersh Aavartan (Aavartan means repetition) is performed on "Sankashtee Chaturthee" which falls on the fourth day after the Full Moon day every month - Krishn Chaturdashee. Chaturthee coinciding with Tuesday is known as "Angarikee". Atharv Sheersh Aavartan carries a great significance on Sankashtee Chaturthee. However, if due to any reasonable constraints it is not possible to perform Atharv Sheersh Aavartan on Chaturthee, it can be performed on any other convenient auspicious day.

It is believed that Lord Ganesh removes sorrows and brings happiness in life by worshiping Lord Ganesh and performing Atharv Sheersh Aavartan. Most effective Aavartan is Sahastraavartan (1000 times), however, 108 or 21 Aavartan are also very common and beneficial.

Note - During Aavartan if possible perform Abhishek to Ganesh Moorti. After Abhishek, perform Shodashopachaar Poojaa of Lord Ganesh.
--If you perform Aavartan in the morning, take the fasting food (fasting food means food to be eaten on that day) like Saaboodaanaa (tapioca) Khichadee, fruits, milk/coffee/tea etc...
--If you perform Aavartan in the night, ensure Aavartan is complete by the moonrise time. Take regular food after offering Nevaidya to Lord Ganesh.

How to Do Aavartan
One Aavartan begins from Upanishad i.e. "Hari Om Namaste Ganapataye... || 1 ||" and ends at "Vighn naashine varad Moortaye Namah...|| 10 ||" before "Phal Shruti".

Start with Shaanti Paath, then complete the first Aavartan up to the end of Asht Naam Ganpati || 10 ||,
Then start the 2nd Aavartan from Upanishad || 1 ||,
repeat the Aavartan as decided.
End the last Aavartan with Phal Shruti.