Most couples will use music during the ceremony to highlight key and emotional moments like the exchanging of the rings, the lighting of a unity candle or during the breaking of the glass. Sometimes, couples will decide that they want to use music as an actual component of the ceremony itself to convey different feelings or to maintain a flow during the ceremony. There is no “correct” piece or tune for different parts during the ceremony, but some popular, classical selections are Schubert’s “Ave Maria” or Puccini’s “O mio babbino caro.”
However, you can always select a popular modern piece like U2’s “All I Want is You” if that fits better with the tone or feel of your ceremony and it makes you more comfortable. One always popular selection is “Amazing Grace” but don’t feel limited by what you have heard at other weddings or what is considered traditional. It is completely up to you and if you would rather stick to sacred music, ask your officiant to provide you with a list of religious solo pieces.