Hundreds of thousands of people flooded the streets of Dublin as St Patrick's Day parades and festivals took place across Ireland and the world.
Enjoying the day in Dublin
Brian Boru, an Irish wolfhound named Paddy and Viking Sitric where among the spectacular sights and sounds on the 1.6 mile (2.6km) route from O'Connell Street to St Patrick's Cathedral.
The Dublin parade was one of the largest in the world, where the theme was Let's Make History and the first of a three-year programme. The next two years will look at the present and future.
Dozens of elaborately decorated floats portrayed the theme and colour of a carnival while marching bands entertained one of the biggest crowds in the city for the March 17 festivities.
President Michael D Higgins attended the event with his wife Sabina and urged people to think of those who have emigrated from Ireland in recent years.
"It continues to play a significant role in defining us as a society and as a people," he said.
"Today we celebrate our wider and diverse Irish family, to whom we remain connected by a strong cultural heritage and history. We are grateful for all they do to keep that heritage alive in their adopted homelands across the globe, as well as for their interest in, and tangible support for, Ireland's welfare and development.
"Today is a special day for all those Irish communities great and small across the world that come together in a spirit of pride and joy to celebrate their identity and their links of affinity and affection with their homeland of origin."
Onlookers enjoy the Dublin St Patrick's day parade as it makes its way down O'Connell Street towards St Patrick's Cathedral.
The parade from Dublin was streamed online to a worldwide audience and an Irish diaspora of about 70 million.
More than 100 international landmarks were turned green to mark St Patrick's Day, including the Great Wall of China, and not to ignore the celebrations the Irish cricket team weighed in with a nail-biting victory over Zimbabwe in the World Twenty20 competition.
The zebra crossing on Abbey Road in London is turned green.
The earliest parade was held in Dingle, Co Kerry at 6am while the shortest took place in West Boylston in the US state of Massachusetts, where 200 people marched through a car park between two pubs in the town Finders and Keepers.
The early morning parade in Dingle, Co Kerry
One of the biggest parades in Northern Ireland was held in Downpatrick, Co Down, where an estimated 30,000 people crowded the streets.
Dr Tim Campbell, director of the town's St.Patrick's Centre, said: "We've taken the politics out of the day, and many other towns are following in our footsteps. We just want people to have a fun day."
There were parades as well in Omagh, Strabane, Enniskillen, Armagh and Derry.
People silhouetted against the skyline, as the annual St Patrick's Day climb of Slemish mountain gets underway in Co Antrim. Slemish is said to be where the boy slave Saint Patrick tended herds for his master Miluic in the 5th century, and ever since has been a place of pilgrimage on St Patrick's Day. Pic: Paul Faith/PA Wire
Belfast's held its St Patrick's Day parade - one of the biggest ever, according to Lord Mayor Mairtin O'Muilleoir - yesterday.
A small crowd of loyalists, some carrying Union flags gathered outside City Hall today. There was a heavy police presence in the area to prevent any trouble.
Organisers of the Dublin parade put the crowds at more than half a million - well up on last year's figures.
Spectators smile as they watch the annual St. Patrick's Day parade in Montreal, Canada. Pic: AP/The Canadian Press, Graham Hughes
More than 3,000 performers took part in the carnival, with Irish sporting hero, Tour de France winning cyclist Stephen Roche the grand marshal as Ireland welcomes the Giro d'Italia bike race in a few weeks.
Susan Kirby, St Patrick's Festival chief executive, said: "The festival parade is true testament to the artistic talent we have here in Ireland, talent that is showcased on a global stage today as the parade is viewed by millions the world over."
A child taking part in a St Patrick's Day parade in Bucharest, Romania. Pic: AP Photo/Andreea Alexandru/Mediafax)
A number of marching bands earned awards for their performances at the parade including the Owasso High School Marching Band, from Oklahoma in the US which was picked the overall best band while the Spirit of the Parade Award went to the Clondalkin Youth Marching Band, from Dublin.
Participants cheer along the parade in New York. Pic: AFP/Emmanuel Dunand