British-born Italian teenager Carlos Acutis who died in 2006 will be canonised by Pope Leo on Sunday, making him the Catholic Church's first ever millennial saint.
The ceremony will take place in St Peter's Square at the Vatican and will be attended by thousands of pilgrims.
Having passed all the posthumous trial necessary for sainthood, he was initially set to be canonised in April, but the ceremony was postponed when Pope Francis died.
It was Francis who had willed Acutis' sainthood forward as he believed the church needed someone like him to attract young Catholics to church.
But what does it take to be raised to sainthood and how did Acutis achieve it?
