The readings at Mass are taken based on the feast day ranking.
In the liturgy of the Catholic Church, a feria is a day of the week other than Sunday.
In recent official liturgical texts in English, the term weekday is used instead of feria.
If the feast of a saint falls on such a day, the liturgy actually celebrated may be that of the saint, not that of the feria (the weekday liturgy). Accordingly, in actual liturgical practice a feria or ferial day is "a weekday on which no special ecclesiastical feast is to be celebrated".
A memorial in the Roman Rite of the Catholic Church is a lower-ranked feast day in honour of a saint, the dedication of a church, or a mystery of the religion.
All feast days are ranked according to their importance and named either as “solemnities", or "feasts", or "memorials".
A solemnity is, in the liturgical calendar of the Roman Rite, a feast day of the highest rank celebrating a mystery of faith such as the Trinity, an event in the life of Jesus, his mother Mary, or another important saint. Unlike feast days of the rank of feast (other than feasts of the Lord) or those of the rank of memorial, solemnities replace the celebration of Sundays outside Advent, Lent, and Easter
