The Catholic Church assigns one date out of the year for each and every canonized saint — known as the saint’s feast day. The saints are remembered on their individual feast days with special mention, prayers, and possibly a scripture reading.
A saint’s feast day can be the day of their actual death or a day assigned by the Church. Typically, the Church only assigns a day when the day of death is unknown or if several other saints are already assigned to that day. The number of canonized saints, however, is greater than the number of days in a calendar year. So two or more saints often share the same feast day. Because overlap often occurs, and the Church isn’t sure of the date of death of some saints, other calendar dates are sometimes chosen — such as the day that the saint was canonized.
Some saints’ feasts are only celebrated in the particular saint’s town or country. Others are internationally celebrated.