The practices of the month
Devotees rise before dawn and bathe in a river or with river water (Kartika snan) throughout the month. Lamps of ghee or sesame oil are offered to Vishnu every evening, and floated on rivers or hung in the sky on tall poles (akash deep) for the ancestors. Tulasi is worshipped daily with a lamp at its foot. Many eat one meal a day, avoid certain foods, sleep on the floor, recite the Damodarashtakam and read the Kartika Mahatmya.
Its festivals
Kartika holds the year's greatest festivals: Karwa Chauth and Ahoi Ashtami before Diwali in the north; the five days of Diwali from Dhanteras to Bhai Dooj; Chhath, the worship of the Sun in Bihar; Akshaya Navami; Prabodhini Ekadashi, when Vishnu wakes from his four months' sleep; Tulasi Vivah; and Kartika Purnima, Dev Deepawali, when Varanasi's ghats glow with a million lamps and Shiva is honoured as Tripurari. Guru Nanak Jayanti also falls on Kartika Purnima.
Why it is so honoured
The Skanda and Padma Puranas say that small acts of devotion in Kartika, a single lamp, a bath before dawn, a tulasi leaf offered, bear the fruit of great sacrifices. It is the month in which Vishnu wakes and Shiva destroyed the three cities, and in which Kartikeya, after whom it is named, was born under the Krittika stars.