Outside of the Mass, prayers of petition are the type of prayer with which we are most familiar. In them, we ask God for things we need—primarily spiritual needs, but physical ones as well. Our prayers of petition should always include a statement of our willingness to accept God's Will, whether He directly answers our prayer or not. The Our Father is a good example of a prayer of petition, and the line "Thy will be done" shows that, in the end, we acknowledge that God's plans for us are more important than what we desire.

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​Prayers of expiation, in which we express sorrow for our sins, are one form of prayers of petition. In fact, the first form because before we ask for anything, we should acknowledge our sinfulness and ask God for His forgiveness and mercy. The Confiteor or Penitential Rite at the beginning of Mass, and the Agnus Dei (or Lamb of God) before Communion are prayers of expiation, as is the Act of Contrition.