The Catechism in Questions & Answers

378. How do we experience the visible side of the church of Jesus Christ?

Among other things, we experience the visible side of the church when human beings act in the church. This is perceptible, for example,

when people profess Jesus Christ,
when divine services are celebrated,
when water is consecrated for baptism and the act of baptism is performed,
when the ministers consecrate bread and wine for Holy Communion and dispense Holy Communion,
when the Apostles lay their hands upon believers and perform the act of Holy Sealing,
when the ministers preach,
when people pray,
when charity is practised.