Generally speaking, outside of the liturgy one bows to the altar if Christ is not present on the altar; one genuflects toward the tabernacle, or toward the altar if Christ is present on the altar (e.g., in the monstrance during eucharistic adoration) or in a tabernacle behind the altar. During the liturgy, one bows or genuflects according to the prescribed liturgical rubrics.
Audrey:
And what is the difference between a bow and a profound bow?
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