India's Prime Minister Narendra Modi has led thousands in a mass yoga programme in the capital, Delhi, on the first ever International Yoga Day.
Mr Modi did stretches, bends and breathing exercises with 35,000 school children, bureaucrats and soldiers.
Security was tight in the city with thousands of police and paramilitary deployed for Sunday morning's event.
Millions of others are expected to do yoga at similar events planned in hundreds of Indian cities and towns.
Mr Modi, a yoga enthusiast who says he practises the ancient Indian art daily, lobbied the United Nations to declare 21 June International Yoga Day.
Thousands of colourful mats were laid out on Rajpath - King's Avenue - where the main event was held.
Officials had earlier said the prime minister will attend the event and address the gathering, but not do yoga.
But Mr Modi surprised participants by joining in with the exercises.
On glacier and at sea
Authorities said 35,000 people attended the 35-minute yoga session on Rajpath, aimed at setting a new Guinness World Record for the largest yoga class at a single venue.
Guinness officials said they would announce the results in a few hours.
Yoga was also being performed on the Siachen glacier and the high seas, the defence ministry said.
The day is also being celebrated around the world and Indian Foreign Minister Sushma Swaraj says "tens of millions" will do yoga on Sunday.
Ms Swaraj herself will be in New York where she will attend the celebrations with UN Secretary General Ban Ki-moon. In Times Square, 30,000 people are expected to do yoga.
But the day, being billed as one to promote "harmony and peace", has hit a controversial note with some Muslim organisations saying yoga is essentially a Hindu religious practice and is against Islam.
Many others say Mr Modi's Hindu nationalist government has an agenda in promoting the ancient Indian discipline.
However, the authorities deny the charge - they say participation in the yoga day is not mandatory and reports that Muslims are opposed to yoga are exaggerated.
International Yoga Day in numbers:
- 35,000 officials, soldiers and students attend the main event on Rajpath in Delhi, including PM Narendra Modi
- 300m rupees ($4.67m; £2.97m): Cost of Delhi event
- 650 of India's 676 districts participating
- Of the 193 UN member countries, celebrations will be held in 192 countries - the exception is Yemen, because of the conflict there
- Events being held in 251 cities in six continents
- 30,000 people to perform yoga in Times Square in New York
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