Easter Sunday is the beginning of the Easter season, sometimes called Eastertide, which lasts for 50 days until Pentecost Sunday. Like Christmas, the liturgical season lasts much longer than just a day. As such the idea of new birth and resurrection factor into the celebration of the mass through this time. The Asperges, which is a rite of sprinkling of the congregation with Holy Water, may be performed on Sundays through lent. The rite is a reminder of our Baptism.
During the rite, the priest will bless water, and may add some salt, then using a branch of hyssop or sprinkler, will proceed to sprinkle himself, the deacons and servers, and then go through the congregation sprinkling and singing an antiphon or hymn as he does so.
Holy Water isn’t just used for this symbolic rite. It’s also found at the entrances of church buildings throughout the year. People entering can dip their hands and bless themselves, again as a symbol and reminder of Baptism. This is done by making the Sign of the Cross.