Who was St David?
St David - or Dewi Sant in Welsh - was born on the south-west coast of Wales, near to where the city of St Davids is today.
We don't actually know the exact year when he was born, but it is believed to be some time in between 462 and 515 AD.
There are many stories about miracles happening around St David.
One of the famous stories is from when he was speaking to a large crowd and someone in the crowd shouted: "We won't be able to see or hear him."
Then, the ground David stood on is said to have risen up so that he was standing on a hill, making it easier for everyone to see him.
It is said that he lived for more than 100 years and died on Tuesday, 1 March 589.
How is St David's day celebrated?
The National St David's Day parade is held in the centre of Cardiff every year, with lots of exciting performances by dragons and theatre groups.
Usually, many children take part, wearing traditional Welsh clothing and performing traditional dances.
Across the country, lots of towns and villages host their own parades and concerts, including a special dragon parade in the small city of St Davids in Wales.
Three facts about St David
1. He was a vegetarian
St David and his monks ploughed fields by hand and didn't eat meat. It is also believed that St David himself only ate leeks and drank water.
2. His words live on
His last words to his followers before his death are thought to have been: "Be joyful, keep the faith and do the little things that you have heard and seen me do." The phrase gwenwch y pethau bychain mewn bywyd - 'Do the little things in life' - is still a well-known phrase in Wales.
3. He left his mark
It is said that he went on a special religious journey to Jerusalem and brought back a stone with him. The stone now sits on an altar in St David's Cathedral, which was built on the site of David's original monastery.
Learn to speak Welsh!
Bore da (Boh-reh dah) - Good morning
Prynhawn da (Prin-houn dah) - Good afternoon
Croeso I Gymru (Croy-so ee Gum-ree) - Welcome to Wales
Diolch (Dee-olch) - Thank you
Dydd Gŵyl Dewi Hapus (dee-the goil De-wi ha-peece) - Happy St David's Day
