Canonization
The process of canonisation involves proving that the person lived in a way that justifies this decision. They must have loved others and loved God. In the Catholic Church, at least two miracles by the saint's intercession must be proven. This means that, because the person is believed to be in heaven, someone must pray, or ask, for the saint to pray for them in heaven. If the prayer is answered and a miracle happens, then they know that the person is a saint. The miracles prove that the saint must be in heaven with God, and able to ask God for prayers to be answered.