Entitled: "Four choir or altar boys, at the wedding of Mrs. Charles de Loosey Oelrichs (Marjorie R. Trumbull). A choirboy is a boy member of a choir, also known as a treble. An altar server is a lay assistant to a member of the clergy during a Christian religious service. An altar server attends to supporting tasks at the altar such as fetching and carrying, ringing the altar bell and so on.