Every year May Day is used to mark many things - from the coming of spring in the Northern Hemisphere to the fight for workers' rights.
Here are some of the events that have taken place to mark the day from Indonesia to Mexico.
Thousands of people gathered in cities across Russia for what is a major public holiday. The largest celebration took place in Moscow's Red Square.
This boy was particularly enthralled by the traditional costumes, balloons and flags on display.
Workers held a protest march in the Indonesian capital of Jakarta. May Day has long been associated with workers' rights in many parts of the world. But there were sporadic clashes between demonstrators and police during the Jakarta rally.
There was also a May Day protest by migrant workers in Hong Kong.
Rallies were held in major cities across France, where trade unions hold traditional parades on May Day. This image shows marchers in Strasbourg.
Police in Turkey prevented demonstrators from marching on Istanbul's Taksim Square.
In Lisbon, Portugal, protesters carried a giant puppet depicting Prime Minister Antonio Costa.
In South Africa workers took part in a rally north of Durban that was organised by the country's largest trade union.
Cuban soldiers held in large parade in Havana. Former President Raul Castro was among those attending.
Venezuela's opposition leader Juan Guaido addressed a rally in Caracas. He had called for a massive protest to increase pressure on President Nicolás Maduro.
But the day is not a political event for everyone. In southern Germany, the annual maypole festival features traditional dancing and music.
In China, May Day marks a national holiday where people often travel. In this image, Chinese paramilitary police stand guard while people visit the promenade on the Bund in Shanghai.
In Bangladesh, traditional musicians participated in a rally in the capital Dakha.
In Britain, too, the day is seen by some as an opportunity to show off a traditional form of dance. These Morris dancers managed to catch the sunrise in Yorkshire.
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