“Jubilee” is the name given to a particular year; the name comes from the instrument used to mark its launch. In this case, the instrument in question is the yobel, the ram’s horn, used to proclaim the Day of Atonement (Yom Kippur). We can find an early indication of it in the Bible: a Jubilee year was to be marked every 50 years, since this would be an “extra” year, one which would happen every seven weeks of seven years, i.e., every 49 years (cf. Leviticus 25:8-13).

In 1300, Pope Boniface VIII called the first Jubilee, also known as a “Holy Year,” since it is a time in which God’s holiness transforms us. The frequency of Holy Years has changed over time: at first, they were celebrated every 100 years; later, in 1343 Pope Clement VI reduced the gap between Jubilees to every 50 years, and in 1470 Pope Paul II made it every 25 years.