Parades and festivals were held throughout Ireland for Saint Patrick's Day on Saturday, while the global diaspora also joined in the party in honour of the Emerald Isle's patron saint.
Debt-ridden Ireland shrugged off economic austerity measures to mark the national holiday, with more than half a million revellers on Dublin's streets to celebrate all things Irish.
At least 60 million people worldwide claim Irish heritage and the feast day has become a firm fixture in the party calendar around the world.
There are parades around the globe, based on "craic", or fun, music, green-coloured beer and fancy dress echoing the island's favourite mythical creature -- leprechauns.
Irish ministers were deployed throughout the world promoting the message that the republic's economy is recovering, while international landmarks were lit up green to join in the revelry.
The centrepiece of the celebrations, the Dublin parade and its marching bands, brought more than half a million people onto the capital's streets, police said, with about 120,000 of them thought to have come from abroad.
The Dublin parade involves marching bands from Britain, Russia and the United States and it was to be reviewed on its 2.7-kilometre route through the city by President Michael D. Higgins and Dublin Lord Mayor Andrew Montague.
The party provides a traditional early kick-start to the tourist season, bringing in a much-needed injection of 43.5 million euros ($56.8 million) to the Irish economy.
Landmark sites throughout the world, including the Leaning Tower of Pisa, Niagara Falls, the London Eye observation wheel, the Burj al Arab hotel in Dubai, the Cibeles fountain in Madrid, the Palace of Culture and Science in Warsaw and Table Mountain in Cape Town were to be illuminated green.
In Britain, Catherine, the Duchess of Cambridge, presented traditional sprigs of shamrock to members of the 1st Battalion Irish Guards, and met their regimental mascot, an Irish wolfhound called Conmeal.
Her husband Prince William is the regiment's honorary colonel.
Irish Prime Minister Enda Kenny and most members of his government are out of the country celebrating with the Irish diaspora.
There are 12 senior ministers and five junior ministers visiting countries like Britain, China, Singapore, the United States, Canada, Germany, France, Italy, Belgium, Finland, Sweden, Australia and New Zealand.
Kenny is in the United States where he is due to present the customary bowl of shamrock -- Ireland's three-leafed floral emblem -- to President Barack Obama at a celebration in the White House on Tuesday.
Obama has links with Ireland through an ancestor who emigrated from the small midlands town of Moneygall in 1849 and he visited the country last year to meet some of his cousins.
Some 34 million people in the United States claim some Irish ancestry -- about eight times the population of the Republic of Ireland.
In his message for the national holiday, Higgins said Irish people had a "love for life", a "sense of fun" and an "innate spirit of hope and optimism".
"The Irish are an enterprising and resilient people. While navigating very difficult economic conditions, we refuse to succumb to defeat or fatalism," he said.
"This indefatigable spirit has in the past ensured our survival and is now a source of our creativity and purpose."