|My mother, Mary Alice, in 1996|
Christians, living and deceased, are united with one another in the Communion of Saints. When we pray on behalf of or in memory of others, we are expressing our bond of unity with the Church on Earth, with the dead who are being purified, and with Jesus and the saints in heaven.
Although today is my mother's anniversary, I actually pray for her and for all my deceased relatives, everyday, morning and evening.
Here is the prayer that I usually use to pray for the deceased. The pronoun can be adjusted for singular, plural, male or female. My example is for my mother, Mary Alice.
Eternal rest, grant unto her, O Lord, and let the Perpetual Light shine upon her. May her soul, and all the souls of the Faithful departed, through the mercy of God, rest in peace.
Note: for more on praying for the dead, here is an essay that explains some misconceptions about praying for the release of souls in Purgatory.