A holy day of obligation is a day on which Catholics are required to attend Mass. In the US, there are six holy days of obligation: New Yr’s Day (January 1), Epiphany (January 6), Ascension Thursday (40 days after Easter), Assumption of Mary (August 15), All Saints’ Day (November 1), and Christmas (December 25).
The duty to attend Mass on holy days of obligation is predicated on the Church’s educating that the Eucharist is important for our non secular well-being. The Eucharist is a sacrament through which we obtain the Physique and Blood of Christ. It’s a time of nice grace and blessing, and it is a chance for us to develop nearer to God.