Thousands of people have lined the streets in towns and cities across Ireland and around the world to watch St Patrick's Day parades, with the parade in Dublin said to be the largest ever.
Late Late Show presenter Patrick Kielty, the grand marshal of the national parade in Dublin, described Ireland's national day as "the biggest party in the world".
More than 4,200 participants took part in the flagship parade in the capital.
It also included several marching bands and groups of dancers, local sporting clubs and participants representing many nationalities.
The parade featured six large-scale pageants and 11 show pieces.
It began at Granby Row and headed down O'Connell Street before finishing across the city at the bottom of Kevin Street.
The theme of this year's parade was Spréach - the Irish word for spark.
Among the participants were a group examining the theme and the circular economy, a showpiece called 'Dublin Seagulls', as well as 14 marching bands from across Ireland, North America and France.
Public transport in Dublin is operating on a Sunday timetable.
Later, the celebrations in Dublin will move onto the festival quarter at Collins Barracks, where the grounds of the historic heritage site will be transformed into a day-to-night city centre festival.
It will feature a host of performances and events, including a 3,000-capacity covered main stage where Denise Chaila will take to the stage of the 'Halla mór' at 9.30pm.
Meanwhile, the Cork City parade began at 1pm with participants embracing the theme of this year's event - a world of pure imagination. It finished shortly after 2.30pm.
Gardaí estimated over 50,000 people lined Cork city's streets for this year's parade.
The Frank and Walters were this year's Grand Marshals, with the Barrack Street Band accompanying them playing 'After All' - voted the Number One Cork song in recent years.
Lord Mayor Kieran McCarthy took to the street as Willy Wonka, saying the sun came out especially to shine on the 3,500 participants from nearly 60 community groups and organisations who took part.
Among the visitors were a party of 40 from Colonge in Germany to celebrate being twinned with the city for the past 35 years.
There too members of the Knights of Columbus Pipes and Drums Group, who took part in yesterday's New York City parade.
Young Scientist of the year, 17-year-old Sean O'Sullivan, was the Grand Marshall for the parade in Limerick City, while singer Maura O'Connell was Grand Marshall of the Ennis parade.
Marchers set off at 10.30am this morning for the Wexford Town parade which was led by members of the emergency services, including the Order of Malta, Red Cross, fire service, Defence Forces and others.
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While St Patrick's Day falls on 17 March, some parades were moved to yesterday in the US because Sunday is a day of worship for the Christian faithful.
Mr Kielty said that as a man called Patrick, who is from Downpatrick in Co Down, and who attended St Patrick's School, he was "the proudest man in Ireland".
The TV presenter said that it was "a massive honour" to be the grand marshal, adding it was "emotional" for him.
"To be the Patrick at the front of this parade is one of the proudest moments of my life."
"I think St Patrick's Day is so important to people because it gives us all a chance to share in something, it brings a lot of people together. I think sometimes here we maybe take it for granted.
"As someone who has lived abroad and knows what that day means to so many people who are longing for a connection to their lives back home, that's what it's about."
"Especially when you come from the North, growing up, St Patrick's grave was at the Church of Ireland, basically everything that used to happen through some type of binary prism.
"The idea of we're now in a position where we can actually share these things, I think that's why today is so important."
Asked will he be able to enjoy the day with so much pressure on him, he said: "Let's be very very clear, there's definitely going to be a lot of fun squeezed out of this.
"This is normally like my second birthday, so we will definitely be celebrating to the max."
Additional reporting: Evelyn O'Rourke
