Diwali or Dipavali is the Hindu festival of lights, which is celebrated every autumn in the northern hemisphere (spring in southern hemisphere). One of the most popular festivals of Hinduism, Diwali symbolises the spiritual "victory of light over darkness, good over evil and knowledge over ignorance". During the celebration, temples, homes, shops and office buildings are brightly illuminated. The preparations, and rituals, for the festival typically last five days, with the climax occurring on the third day coinciding with the darkest night of the Hindu Lunisolar month Kartika. In the Gregorian calendar, the festival generally falls between mid-October and mid-November.

In the lead up to Diwali, celebrants will prepare by cleaning, renovating and decorating their homes and offices. During the climax, revelers adorn themselves in their finest clothes, illuminate the interior and exterior of their homes with diyas (lamps and candles), offer puja (prayers) to Lakshmi, the goddess of prosperity, light fireworks, partake in family feasts, where mithai (sweets) and gifts are shared. Diwali is also major cultural event for the Hindu and Jain diaspora from the Indian subcontinent.

The five day festival originated in the Indian subcontinent and is mentioned in early Sanskrit texts. The names of the festive days of Diwali, as well as the rituals, vary by region. Diwali is usually celebrated eighteen days after the Dussehra festival with Dhanteras, or the regional equivalent, marking the first day of the festival when celebrants prepare by cleaning their homes and laying floor decorations, such as rangoli. The second day is Choti Diwali, or equivalent in north India, while for Hindus in the south of India it is Diwali proper. Western, central, eastern and northern Indian communities observe Diwali on the third day and the darkest night of the traditional month. In some parts of India, the day after Diwali is marked with the Goverdhan Puja and Diwali Padva, which is dedicated to the relationship between wife and husband. Some Hindu communities mark the last day as Bhai Dooj, which is dedicated to the bond between sister and brother, while other Hindu and Sikh craftsmen communities mark this day as Vishwakarma Puja and observe it by performing maintenance in their work spaces and offering prayers.

Some other faiths in India also celebrate their respective festivals alongside Diwali. The Jains observe their own Diwali, which marks the final liberation of Mahavira, the Sikhs celebrate Bandi Chhor Divas to mark the release of Guru Hargobind from a Mughal Empire prison, while Newar Buddhists, unlike other Buddhists, celebrate Diwali by worshiping Lakshmi. The festival of Diwali is an official holiday in Fiji, Guyana, India, Malaysia (except Sarawak), Mauritius, Myanmar, Nepal, Singapore, Sri Lanka, Suriname, and Trinidad and Tobago.