Whenever a priest, deacon, or extraordinary minister of holy Communion distributes the Eucharist to the sick or homebound, they will use a pyx.
According to the Catholic Encyclopedia, "The word pyx (Lat., pyxis, which transliterates the Greek, pyxis, box-wood receptacle, from pyxos, box-tree) was formerly applied in a wide and general sense to all vessels used to contain the Blessed Eucharist."
Originally a pyx would be suspended over the altar and was a primitive form of a tabernacle.
Eventually the pyx became associated chiefly with the small usually golden receptacle that is used to carry the consecrated hosts to the sick or homebound.
Often the communion pyx is worn around the neck, reminding the individual carrying it, as well as those around them, that they are carrying the Blessed Sacrament.
Sometimes a pyx is carried in a small purse-like bag that is designed to further protect the pyx and the consecrated hosts inside it.
Above all, the pyx is meant to be handled with great care, recognizing that anyone who holds it with the Eucharist inside is holding Jesus, the Lord.