November 15 :   
Kartik Poornima celebrated on the 15th of the full moon day of Kartik (November-December), alluding to Shiva's destruction of the demon Tripura. It signifies the subjugation of evil and fostering goodness. Fireworks and lamps are lit in celebration of the victory. It is therefore also called the Dev-Deepavali or Diwali of the Gods. The ghats of Varanasi come alive with thousands of brightly-lit earthern lamps. Visitors throng in large numbers to watch this spectacular event.
Kartik is the eighth lunar month of the Hindu year when the sun is Krittika or Pleiades. Kartik is perhaps the holiest of all the months in the Hindu calendar characterised by many religious festivals. 
The Mahatme (significance) of Kartik has been elaborately dealt with in the Uttar Khand of Padma Puran. In the dialogue with King Dilip, the wise sage Vasishta refers to Kartik Mahatme by illustrating various significant legends pertaining to the month as the most efficacious means of obtaining salvation. 
Satyabhama asks of Krishna as to how the Kartik month came to be regarded as holy. In reply, Krishna relates the story of Sankha Asura, the demon who carried away the Vedas into the sea and how Vishnu had to take the incarnation of mastya (Fish) and kill Sankha Asura (conch shell demon) and restore the Vedas to the Gods - a quest for truth and enlightenment. This incarnation is said to have taken place on the 11th day of Kartik and is commemorated by all devout Hindus through bathing and prayers at Praying and Badarkashrama. 
It is said Lord Krishna himself stressed the importance of religious observances during Kartik to Satyabhama. He disclosed that in her previous life she herself had been a Brahmin's daughter and was his consort in consequence of the Vratas she had performed during this month. 
Another interesting tale goes thus. Once, Dhaneswara, a man of low caste, went to the banks of the Narmada to sell skins. There, he was thrown in the company of pilgrims. He watched their religious performances and was prompted to join them more out of curiosity then devotion. But even this was enough to secure him heavenly bliss. 
Though Diwali is the foremost festival heralding the Kartik month, there are another important festivals during the month of Kartik. 
Kalashtami: The eighth day of the second half of the month of Kartik is observed by fasting in Banaras and the night is spent in prayers. Legend has it that on this day Kala Bhairav, a creation of Lord Shiva, in his wrath chopped off one of the five heads of Lord Brahma and repaired to Banaras. Since then Kala Bhairav has been the presiding deity of the sacred city. The local Hindus observe this day annually in his honour. 
Kushmand Ninth: This is the ninth day of the dright fortnight of kartik, named after Kushmand or pumpkin. Legend has it that there was a Brahmin who had two sons named Dhananjaya and Krishna. Both led dissipated lived and on their death while Dhananjaya attains heaven, Krishna is sent to hell. The reason was that Dhananjaya as advised by their religious teacher had taken baths in the Ganges during this month and given a gift of pumpkin filled with gold to a Brahmin, while his brother had not. Even today, people take a dip in holy rivers and gift something to Brahmins and the poor. 
Akshay Navami: The ninth day is recognised is Akshay Navami or the inexhaustible Ninth. On this day, Sun God worshipped Durga and was in return awarded with unlimited gifts in the form of solar properties which are now so beneficial to mankind. The main characteristics which lends the epithet `Aksh' or Indestructible to this day is that gifts bestowed on this particular day continue to bear blessings for ever. Hindus spend the day in meditation and prayer to acquire the inexhaustible knowledge of God and thereby attain eternal bliss and peace. 
Akshay Navami is also associated with the happy reunion of Bharata with Rama when the latter was returning home after his 14 years of banishment. 
Haribodhini or Prabodhini:This is the 11th day of Kartik bright fortnight or the Kartik Ekadashi and is regarded as the day of Lord Hari or Vishnu. Haribodhini means that which bestows the knowledge of Sri Har, and Prabodhini meaning awakening from sleep (of Vishnu after four months) or more aptly, ignorance. Devotees observe fasts and rigorous penances to seek knowledge. All meritorious actions done on this day are said to yield thousand-fold credits. Perhaps this has the link with Sun's movement to the southern hemisphere and the Winter Solsticce. 
Moreover, the famous Kartik meals or fairs are held annually at Gurumukteswar on the banks of the Ganges, attended by thousand of pilgrim from far and near. The religious significance of this place lies in the fact that it was at this site that, according to the epic Mahabharata, King Shantanu met goddess Ganga in her human form and married her. Scriptures opine that great merit can be obtained by bathing in the Ganges specially on this day. 
Vaikunth Chaturdashi:The 14th day of the first half of Kartik is said to be sacred to Vishnu, the Lord of Vaikunth. It is revealed on this day in Krita yuga Vishnu worshipped Shiva at the Manikarnika Ghat in Benaras. While offering 1,000 lotus flowers and invoking Shiva with praises, he found the thousandth lotus missing. But Vishnu, unshaken, completes his worship by replacing the missing lotus with one of his own eyes. Shiva veritably pleased with this gesture presented Vishnu with the Sudarshan Chakra. Since then, devotees of Vishnu offer him a thousand lotuses and chant Vishnu Sahsranama. 
Vysa Puja: On Kartik Full Moon day, Vyasa, the famous compiler of the Vedas is worshipped, and in his name all regular expounders of the Purans are also worshipped. A similar day is Ashada Full Moon, known as Guru Puja when every student worships his own Guru.