These lay people are sometimes referred to as Eucharistic Ministers.
These special ministers of communion enjoy the unique privilege of assisting the clergy with distribution of the Body and Blood of Christ at Mass. Some take communion to those of us who are not able to come to church (housebound, those in convalescent home, etc). A special minister may function in both capacities or in just one of the two.
Parishioners 18 years of age and above, who have received all three sacraments of initiation (Baptism, Eucharist and Confirmation) are eligible and invited to participate in this ministry.