What is the wafer at communion?
Sacramental bread
The General Instruction of the Roman Missal §321 recommends that "the eucharistic bread ... be made in such a way that the priest at Mass with a congregation is able in practice to break it into parts for distribution to at least some of the faithful. ... The action of the fraction or breaking of bread, which gave its name to the Eucharist in apostolic times, will bring out more clearly the force and importance of the sign of unity of all in the one bread, and of the sign of charity by the fact that the one bread is distributed among the brothers and sisters."