Kali means Dark (evil) and Chaudas - Fourteenth. Thus, celebrated 14th day of Ashwin, Kali Chaudas is the day allotted to the worship of Maha-Kali or Shakti and is believed that on this day Kali killed the wicked Raktavija. Also referred to as Narak-Chaturdashi, Kali Chaudas is day to abolish laziness and evil which create hell in our life and shine light on life. The strength to protect others is referred as Kali, and if its used for God's work it is called Mahakali.
Kali Chaudous is also attached to the legend of Lord Hanuman. Hanumanji as a baby was very hungry. Whilst lying down he saw the sun in the sky and thought it was a fruit and went to pick it. He flew into the sky and put the whole sun in his mouth causing darkness throughout the entire universe. Lord Indra requested that Hanumanji return the sun. When Hanumanji refused, Lord Indra unleashed his vajra and knocked Hanumanji down to earth releasing the Sun.
On this day we offer poojan to Hanumanji as our Kuldev to protect us from Evil. The poojan is performed with oil, flowers, chandan and sindur. Coconuts are also offered to Hanumanji and prashad of Sesame seed, ladoos and rice with ghee and sugar.
The rituals of Kali Choudas is strongly suggestive of the origin of Deepavaali as an harvest festival is performed. On this day delicacies are prepared from pounded semi-cooked rice (called Poha or Pova). This rice is taken from the fresh harvest available at that time. This custom is prevalent both in rural and urban areas especially in Western India.
On this day, a head wash and application of kajal in the eyes is believed to keep away the kali nazar (evil eye). Some say that those who are into tantra, learn their 'mantras' on this day. Alternatively, people offer Nived (food) to the goddess that is local to where they are originally from. This goddess is called their 'Kul Devi', in order to cast off evil spirits. Some families also offer food to their forefathers on this day. The second day of Diwali is known as Kali Choudas in Gujarat, Rajasthan & few part of Maharashtra. This reverence is called "Kali Chaudas or Kal Chaturdasi".