Subdeacon sits at the top of what Western canon law once called the minor orders, a set of lesser clerical ranks, including porter, lector, exorcist, and acolyte, that a candidate for priesthood traditionally passed through on the way to the major orders of deacon, priest, and bishop. The Latin Church abolished the subdiaconate as a distinct order after the Second Vatican Council, replacing the old sequence with the two instituted ministries of lector and acolyte for seminarians and lay ministers alike, but Eastern Christianity, including the Eastern Catholic churches that share the Byzantine liturgical tradition, kept the subdiaconate as a living rank.
In the Byzantine rite a subdeacon is ordained through the cheirothesia, a blessing given outside the sanctuary rather than the cheirotonia performed at the altar for deacons, priests, and bishops, marking it as one degree lower in the hierarchy than the three sacred orders proper. Traditionalist Catholic communities that retain the pre-conciliar Latin liturgical books have also preserved the subdiaconate as they understood it before the reform, so the office continues in more than one living form even where the mainstream Latin Church discontinued it.