The celebrations of Diwali differ from region to region.
There are many legends associated with Diwali and its celebrations.
In Northern and Western regions of India, Diwali is celebrated to mark the return of Lord Rama to Ayodhya after defeating and killing the demon king Ravana.
In Eastern states, Diwali is associated with the story of Narakasura, who had become a menace to people.
He is killed by Lord Krishna and his wife Satyabhama.
In Maharashtra and Mysore, Diwali is associated with King Bali.
He was very popular with his subjects for his generosity.
His popularity could not be endured by gods as he was an asura.
They went to Lord Vishnu and beseeched him to cut Bali down to size.
Upon the request of gods, Lord Vishnu went to King Bali in the guise of Vamana, a diminutive Brahmin, and requested the king to give him land equal to three steps.
The generous king agreed.
Then Lord Vishnu occupied earth with one step and heaven with the second step.
He then asked King Bali where he should put his third step.
Bali agreed to take the third step on his head.
Thus Lord Vishnu pushed Bali to the underland.
But, he gave him the lamp of knowledge and allowed him to come up once a year and light lamps to dispel darkness and spread the light of wisdom.
From that time onwards, people have been celebrating his arrival on Bali Padyami.
In Bengal, people celebrate Diwali as part of Kali puja.
Kali is another form of Durga, the most powerful goddess.
Goddess Kali pierces darkness with her strength.
In North and South, people light earthen lamps on the occasion of Diwali.
In the South, people light earthen lamps also on the day of Karthika poornima (full moon day), which falls a fortnight later.
The lights are meant to welcome Goddess Lakshmi to the households, which would result in prosperity.
It is believed that the fireworks would scare away evil spirits.
In Punjab, the day following Diwali is called Tikka.
On this day, sisters prepare a paste with saffron and rice and place it on their brothers' foreheads to ward off all evil.
People in Maharashtra exchange gifts on the second day of Kartika.
There, on Trayodasi, the thirteenth day, a festival honouring a prince taken away by Yama, the god of death, is observed.
The prince's life was taken away four days after his marriage.
Out of compassion for the departed youth, Yama assured that those who observed the day would not be subjected to untimely death.
For this reason, the lamps lighted to commemorate the occasion are positioned facing the south, because southern direction is specified for Lord Yama.
Diwali is celebrated not only in India, but also in many other countries.
With more and more Indians migrating to other countries, Diwali is being celebrated as a major festival across the globe.
Diwali is celebrated in countries such as the US, Britain, Suriname, Canada, Fiji, Australia, Mauritius, Malaysia, Trinidad and Tobago, South Africa, Guyana, Nepal, Sri Lanka, Singapore and Thailand.
There, it is the festival of lights that unites all the people of Indian origin living in that country.
With Indian diaspora present in so many countries, sending gifts assumes great significance as it brings them together on specific occasions such as these.