In the Apostles Creed we affirm:
I believe in the Holy Spirit, the Holy Catholic Church, the communion of Saints, the forgiveness of sins, the resurrection of the body, and the life everlasting.
But what does this 'communion of the saints' really mean?
The communion of saints is a “communion,” a union, a common bond, a profound connection, a great fellowship — shared among the “saints,” the holy ones, the Christian faithful, those who are filled with grace, members of the one body with Christ as the head.
"The communion of saints is the Church” (CatechismCC #946). It has three states or divisions, the communion of saints of the living, those who are still on their pilgrim journey on earth; and the communion of saints of the dead or the faithful departed, some of whom are being purified, those in purgatory, and the communion of saints enjoying eternal glory in the presence of God, those in heaven (CatechismCC #954).