Deva Divali is a Jain

Jainism

Jainism is an Indian religion that prescribes a path of non-violence towards all living beings. Its philosophy and practice emphasize the necessity of self-effort to move the soul towards divine consciousness and liberation. Any soul that has conquered its own inner enemies and achieved the state...

 festival, which takes place during the month of Kartik

Kartika (month)

Kartika , is a month of Hindu and Bengali calendars, named after the Hindu god, Kartikeya....

 in the Indian lunisolar calendar, around the full moon day.(Purnima

Purnima (day)

Purnima is the Indian word for Full Moon. The day of Purnima is the day in each month in which the full moon occurs, and marks the division in each month between the two lunar fortnights...

). This usually falls in October/November.

The festival celebrates the enlightenment of Lord Mahavira, the last of the Jain Tirthankar

Tirthankar

In Jainism, a ' |ford]]-Maker", ) is a human being who achieves moksa through asceticism and who then becomes a role-model and teacher for those seeking spiritual guidance....

of this era, attained Nirvana

Nirvana

Nirvāṇa ; ) is a central concept in Indian religions. In sramanic thought, it is the state of being free from suffering. In Hindu philosophy, it is the union with the Supreme being through moksha...

or Moksha

Moksha

Within Indian religions, moksha or mukti , literally "release" , is the liberation from samsara and the concomitant suffering involved in being subject to the cycle of repeated death and reincarnation or rebirth.-Origins:It is highly probable that the concept of moksha was first developed in...

on this day at Pavapuri on Oct. 15, 527 BC, on Chaturdashi

Chaturdashi

In the Hindu calendar, Chaturdashi is the 14th day of the waxing phase or waning phase of the moon. This is the day prior to new moon or full moon...

 of Kartika, (the 14th day of Kartik’s bright fortnight Shukla Paksha).
This is considered a most auspicious day by Jains.

The festival starts on the 11th day (Ekadashi

Ekadashi

Ekadashi , also spelled as Ekadasi, is the eleventh lunar day of the shukla or krishna paksha of every lunar month in the Hindu calendar . In Hinduism and Jainism it is considered a spiritually beneficial day...

) of Kartik, known as Prabodhini Ekadashi

Prabodhini Ekadashi

Prabodhini Ekadashi is the 11th lunar day in the bright fortnight of the Hindu month of Kartik. It marks the end of the four-month period of Chaturmas, when god Vishnu is believed to sleep...

, and involves a two day circumperambulation (parikrama

Parikrama

For meaning of word see Parikrama .Parikrama is a Rock and Roll band from Delhi, India. They have several live performances and original numbers to their name. The band was officially formed on June 17, 1991 in Delhi...

) around the sacred mountains of Palitana

Palitana

Palitana is a city in Bhavnagar district, Gujarat, India. It is located 50 km southwest of Bhavnagar city and is a major pilgrimage centre for Jains.-History:...

 and Girnar

Girnar

Girnar is a collection of mountains in the Junagadh District of Gujarat, India, situated near Junagadh at a distance of 327 km from Ahmedabad. It is a holy place and an important pilgrimage for both Hindus and Jains. There are a number of temples located here. Amidst the lush green Gir...

, in Gujarat.
The festival ends on the full moon day (Kartik Poornima

Kartik Poornima

Kartik Poornima is a Hindu holy day celebrated on the full moon day or the fifteenth lunar day of Kartik . It is also known as Tripuri poornima and Tripurari Poornima. It is sometimes called Deva-Diwali or Deva-Deppawali - the festival of lights of the gods...

).