What's the history of Saint Patrick's Day?

Last updated at 14:46
Crowds in BelfastPacemaker

Millions of people around the world celebrate Saint Patrick's Day on the 17th of March, every year.

It is a celebration of Irish history and culture, and is a national holiday in the Republic of Ireland and Northern Ireland.

Who was Saint Patrick?

Saint Patrick is the Patron Saint of Ireland and is celebrated for bringing Christianity to the country.

He is thought to have grown up in Britain, during Roman times, but was kidnapped and taken to Ireland as a slave.

Once he was free again, he became a priest, and went back to Ireland to convert thousands of people to Christianity.

The celebration

Saint Patrick's Day started as a religious feast to celebrate Saint Patrick's work, but it's grown to be an international festival of all things Irish.

People take part in parades and dancing, eat Irish food, and enjoy firework displays.

The day is also famous for people wearing shamrocks, dressing up as bearded Irish fairies called leprechauns, and wearing all green.

Here are some of the best shots from the celebrations...

Spectators take a selfie at the St Patrick's Day parade in DublinGetty Images
Spectators in Dublin wear leprechauns' hats at the St Patrick's Day parade
Flute players, Belfast
A flute player joins a parade in Belfast, Northern Ireland
Irish dancers, Belfast
Crowds enjoy watching the Irish dancers in Belfast
Toddler in Belfast
A toddler enjoys a green ice cream
Omagh parade
Someone dressed as St Patrick himself makes an appearance in Omagh, Northern Ireland where he joined the parade down the street by a tractor

And buildings were turned green for the occasion...

The London EyePA
The London Eye
Nelson's Column in Trafalgar Square, LondonPA
Nelson's Column in Trafalgar Square, London
The Trafford Centre in ManchesterPA
The Trafford Centre in Manchester
Empire State Building, New YorkGetty Images
Empire State Building, New York, USA
Reunion Tower in Dallas, TexasTourism Ireland
Reunion Tower in Dallas, Texas, USA
The Ada Bridge in BelgradeTourism Irelnad
The Ada Bridge in Belgrade, Serbia
The Sacre Coeur, ParisGetty Images
The Sacre Coeur, Paris, France