Officially canonised?

17th March is recognised the world over as St Patricks Day. It's celebrated as the day he died, and also known as his Feast Day. He's the Patron Saint of Ireland and lived in the 5th Century AD, although the exact dates for the year of his birth and death are not known.

The problem? Everyone assumes he's a regular, official Saint like the rest of the famous ones, whereas it turns out he's a little different because he wasn't actually canonised. He appears on the List of Saints, and is known as The Apostle of Ireland, so there's no problem with him actually being accepted and treat as one, it's just that there is a formal process which must be followed for the Catholic Church to officially recognise a saint, and for various historical reasons he didn't go through it.

Maewyn Succat

His full name was Maewyn Succat, and he's buried at Down Cathedral in Downpatrick. He's the primary patrol Saint of Ireland, there being three in total - the others are Brigit of Kildare and Columba. He was already treat as the patron Saint of Ireland as early asd the 7th century.

The story of St Patrick isn't without controversy, and it has nothing to do with him being canonised or not. Records of his life and works are so scare there is a theory there were two "Patricks" and what we know as St Patrick today is in fact an amalgamation of them both. If true, the earlier one would be based on Palladius, who was one of the earlier clerics in Ireland around the year 430.

Shamrock

The association of the shamrock with the Irish is said to come from St Patrick. He used the three leaves of the plant to illustrate the Christian message of God the Father, God the Son and God the Holy Ghost.

Clearly, today it  doesn't matter whether St Patrick was officially canonised or not since he is venerated in exactly the same way all the other saints who were, but it's an interesting mass misconception which catches many people out.