Everyone loves to have some fun on St Patrick's Day, and this year was no different. Pregnant Kate Middleton and her husband William made a visit to the Irish Guards Parade at the Aldershot barracks where the Duchess looked stunning in a fittingly-coloured green Emilia Wickstead coat dress. Evidently beaming, Kate, who is five months pregnant, handed out shamrocks to 40 members of the 1st Battalion.
President Barack Obama also got involved in the celebrations, posting a picture of himself on Twitter in Irish pub The Dubliners with a pint of Guinness, tweeting to his almost-30 million followers: "Happy St. Patrick's Day!"
The annual celebration of Ireland's patron Saint creates parades, carnivals and parties all over the world, turning rivers and fountain spouts green, including the White House's fountain, and even lighting up the London Eye in true style of the Emerald Isle. See our best pictures from the world's celebrations...
The pregnant Duchess of Cambridge and her husband William visit the Irish Guards Parade at the Aldershot barracks to mark St Patrick's Day. The couple, who hold the Irish title of Baron and Lady Carrickfergus, arrived in the rainy Hampshire town on Sunday morning - Kate handed out shamrocks to 40 members of the 1st Battalion and embraced the colour of the day by wearing a green Emilia Wickstead coat dress
Belfast celebrates in spectacular style as carnival comes to town, transforming the city centre streets into a sea of colour
President Barack Obama posted a photo on Facebook of himself drinking a pint of Guinness, wishing everyone a "Happy St. Patrick's Day!"
A woman wears false eyelashes with the colours of the Irish flag during the St Patrick's day parade through Dublin city centre
The HMS Belfast is lit green for Tourism Ireland's St Patrick's Day celebrations and to mark the ship's 75th anniversary in London
Washington turns its fountains green. Pictured here, the fountain on the South Lawn of the White House spouts green water in honour of St. Patrick's Day. The Jefferson Memorial and green-water fountain, as seen from the South Lawn of the White House, and the Washington Monument is seen as the water in the fountain runs green, as seen from the South Lawn of the White House in Washington. Bottom right, the O'Riada McCarthy Manning Academy of Dance leap high in the air at the Kansas City Saint Patrick's Day Parade
The London Eye lights up the Thames even more than usual as it is lit green by Tourism Ireland to celebrate St Patrick's Day in London
Parade goers walk along the parade route during St Patrick's Day festivities in Dublin, Ireland. More than 100 parades were held across Ireland to mark St Patrick's Day, the feast day of the patron saint of Ireland, with about 650,000 spectators said to have attended the parade in Dublin
The Chicago River is dyed green before the start of the St Patrick's Day parade in Chicago, a long-standing tradition in the city that began 43 years ago
Onlookers join in the fun of the St Patrick's Day parade and festival in Trafalgar Square
Parade participants brave the snowy weather conditions to play in their band along 5th Avenue during the 252nd New York City St Patrick's Day Parade