St Paddy's Day is not just a celebration of Irish heritage and culture in general. It is also a Christian holiday, embraced by several churches, including the Catholic Church. It commemorates St Patrick himself and the advent of Christianity in Ireland.
St Patrick is said to have used a shamrock (3-leafed clover) to teach the holy trinity. It's also believed that he converted thousands from pagan Irish to Christianity. St Patrick died on March 17th, which is why we celebrate on this day.
Okay, maybe you didn't want to hear all that. After all, putting the seriousness back into what we have come to view as a "fun" holiday isn't what most want to read. So I won't harp on the history lesson.
This is also a day of parades and festivals. Of donning the colour green (because St Paddy himself wore green robes). Of posters and buttons and paper cutouts of 3-leafed clovers. Some cities even die their rivers emerald green to observe the holiday.
Perhaps the most remarkable thing, though, comes from the Church. Yes, just one more time. This one I think you'll pardon me for.
The Church lifts restrictions on eating and drinking alcohol for the day. Even I was surprised about this one. I suspect this might be why so many non-religious non-Irish choose to celebrate.
But regardless of why. Whether or not you are Irish or of Irish decent. Whether or not you honour St Patrick for what he truly represented, may you stay safe and enjoy this annual day of wearing of the green.