Holi is perhaps the least religious of Hindu festivals, but definitely the most colourful. The riotous celebrations involve throwing coloured powders at friends and family, giving the holiday its popular name Festival of Colours.

Holi 2017 Hindu festival colours
Holi 2017 Hindu festival colours
Holi 2017 Hindu festival colours
Holi 2017 Hindu festival colours
Holi 2017 Hindu festival colours

There are several legends behind the origins of this ancient religious festival. One theory is that the colourful ritual is based on the story of Lord Krishna's playful splashing of 'gopis' (wives and daughters of cowherds) with water, but it also celebrates the coming of spring.

Holi 2017 Hindu festival colours
People throw coloured powder at each other to celebrate the Holi festival at a Temple in SiliguriDiptendu Dutta/AFP
Holi 2017 Hindu festival colours
People celebrate Holi, the Festival of Colours, in Agartala, IndiaJayanta Dey/Reuters
Holi 2017 Hindu festival colours
Hindu devotees take part in celebrations for the Holi festival at a Temple in SiliguriDiptendu Dutta/AFP
Holi 2017
A girl reacts as coloured water is thrown into her face while celebrating Holi in MumbaiShailesh Andrade/Reuters
Holi 2017
Devotees are sprayed with coloured water at a temple in AhmedabadAmit Dave/Reuters
Holi 2017
Children play with colours during Holi celebrations in ChennaiArun Sankar/AFP
Holi 2017 Hindu festival colours
Boys smear each other with colors during Holi, the Festival of Colours, celebrations in KolkataRupak De Chowdhuri/Reuters
Holi 2017 Hindu festival colours
A student covered in coloured powder celebrates Holi at Rabindra Bharati University in KolkataRupak De Chowdhuri/Reuters
Holi 2017 Hindu festival colours
A girl shakes coloured powder out of her hair in KolkataDibyangshu Sarkar/AFP
Holi 2017 Hindu festival colours
A college student reacts as coloured powder is thrown into her face during Holi celebrations in AgartalaJayanta Dey/Reuters
Holi 2017 Hindu festival colours
A woman covered in coloured powders attends a Holi event in KolkataDibyangshu Sarkar/AFP
Holi 2017 Hindu festival colours
Students play with coloured powders as they celebrate Holi in KolkataDibyangshu Sarkar/AFP
Holi 2017 Hindu festival colours
Children play with coloured water during Holi celebrations in Chennai, IndiaArun Sankar/AFP
Holi 2017 Hindu festival colours
A reveller, smeared with coloured powder, gestures during Holi celebrations in Agartala, the capital of northeastern Indian state of TripuraArindam Dey/AFP
Holi 2017 Hindu festival colours
Revellers play with colours during celebrations for the Holi festival in SiliguriDiptendu Dutta/AFP
Holi 2017
A man holds a smoke flare while celebrating Holi, the festival of colours, in DelhiCathal McNaughton/Reuters
Holi 2017
Women take part in Holi, the festival of colours, in DelhiCathal McNaughton/Reuters
Holi 2017
A girl reacts as coloured powder is applied on her face in MumbaiShailesh Andrade/Reuters
Holi 2017
A man celebrating the Hindu festival of Holi dumps a bucket of coloured water onto passengers travelling in a rickshaw in Mathura in Uttar Pradesh stateAFP
Holi 2017
A young man is sprayed with coloured powders during Holi celebrations in ChennaiArun Sankar/AFP
Holi 2017
Youths take part in the colourful Holi celebrations in ChennaiArun Sankar/AFP
Holi 2017 Hindu festival colours
Devotees covered with coloured powder carry an idol of Lord Krishna during Holi celebrations at a temple in AmritsarNarinder Nanu/AFP
Holi 2017 Hindu festival colours
A child is covered in coloured powders in ChennaiArun Sankar/AFP
Holi 2017 Hindu festival colours
Youths play with colours during Holi celebrations in ChennaiArun Sankar/AFP
Holi 2017 Hindu festival colours
Students celebrate the Hindu festival of colours in KolkataDibyangshu Sarkar/AFP
Holi 2017 Hindu festival colours
Bollywood actress Vidya Balan takes part in Holi celebrations in Mumbai during a promotional event for her upcoming film Begum JaanAFP
Holi 2017 Hindu festival colours
A student at Guru Nanak Dev University in Amritsar is covered in coloured powders during Holi celebrationsNarinder Nanu/AFP
Holi 2017 Hindu festival colours
Students take a selfie as they celebrate Holi with coloured powder at Guru Nanak Dev University in Amritsar, IndiaNarinder Nanu/AFP
Holi 2017 Hindu festival colours
A schoolboy with his face smeared with coloured powder rides a bike in New DelhiPrakash Singh/AFP
Holi 2017 Hindu festival colours
Hindu devotees decorate the ground around a traditional Holika bonfire made out of cakes of cow dung in AhmedabadSam Panthaky/AFP
Holi 2017 Hindu festival colours
Hindu devotees walk around a traditional Holika bonfire during Holi in AhmedabadAmit Dave/Reuters
Holi 2017 Hindu festival colours
A man holding a child looks at a traditional bonfire made out of cakes of cow dung and coconuts in AhmedabadSam Panthaky/AFP

Being covered in colour brings relative anonymity, and in largely conservative India, this means Holi is a time when men and women and boys and girls can mingle with relative freedom. The city of Vrindavan in northern India is one of the few places where widows can celebrate Holi.

Indian tradition dictates that widows are barred from participating in any celebrations as their presence is considered ominous. Women whose husbands have died are often shunned by society and abandoned by their families. In Vrindavan, however, attitudes are changing, thanks to the work of Sulabh International, a non-profit organisation dedicated to improve the lives of widows. The campaign has been so successful that thousands of widows have flocked to Vrindavan, now known as "the city of widows".

Holi 2017 Hindu festival colours
A widows covered in coloured powder takes part in Holi celebrations in the town of VrindavanCathal McNaughton/Reuters
Holi 2017 Hindu festival colours
Widows celebrate Holi at a temple in the town of Vrindavan in the northern state of Uttar PradeshCathal McNaughton/Reuters
Holi 2017 Hindu festival colours
Widows take part in Holi celebrations in the town of Vrindavan in the northern state of Uttar PradeshCathal McNaughton/Reuters
Holi 2017 Hindu festival colours
Indian widows lead the celebrations of the festival of colours at a temple in VrindavanDominique Faget/AFP
Holi 2017 Hindu festival colours
Widows embrace during Holi celebration at Govinath temple in Vrindavan, IndiaDominique Faget/AFP
Holi 2017 Hindu festival colours
A widow dances during celebrations for Holi in Vrindavan, IndiaDominique Faget/AFP

Holi is primarily observed in India and across the subcontinent, including Pakistan, where security was exceptionally tight around Hindu temples amid growing tensions. Non-Muslims make up only about three percent of the 190 million population of Muslim-majority Pakistan.

Holi 2017 Hindu festival colours
Children buy coloured powders and water pistols in Karachi, PakistanRizwan Tabassum/AFP
Holi 2017 Hindu festival colours
Pakistani Hindu children celebrate Holi in KarachiRizwan Tabassum/AFP
Holi 2017 Hindu festival colours
Boys with their faces smeared in colours take part during celebrations of Holi at the Shri Swaminarayan Temple in Karachi, PakistanAkhtar Soomro/Reuters