All Saints' Day is the solemn Holy Day of the Catholic Church observed annually on November 1st. The day is dedicated to the Church's saints, that is, to all those who have come to heaven. It should not be confused with the Day of All Souls, which is celebrated on November 2, dedicated to those who have died and have not yet reached heaven.
Although millions, or even billions, of people, may already be saints, All Saints' Day celebrations tend to concentrate on identified saints—those honored by the Catholic Church in the canon of saints.
All Saints' Day is also commemorated by adherents of the Eastern Orthodox Church and some Protestant denominations, such as the Lutheran and Anglican churches.
Generally speaking, All Saints' Day is a Catholic Holy Day of Duty, which means that all Catholics are expected to attend Mass on that day unless they have an excellent excuse, such as serious illness.
Many countries have different laws according to their national conferences of bishops. The bishops of each conference shall have the power to change the rules regulating the day's responsibility.
Pope Bonifacio IV, who consecrated the Pantheon to the Virgin Mary and all the Martyrs in Rome on May 13, 609 AD, officially initiated the All Saints' Day. Bonifacio IV has founded the Day of All Souls, which is followed by All Saints.