An anniversary is a day that commemorates an event that occurred on the same day of the year some time in the past.
Birthdays are the most common type of anniversary where the birth date of a person is commemorated.
Wedding anniversaries are also often celebrated on the same day of the year as the wedding occurred.
Most countries around the world celebrate national anniversaries. These can be the date of independence of the nation or the adoption of a new constitution or form of government.
Many anniversaries have special names; for example 25 years is a Silver Jubilee or silver wedding anniversary; 50 years is a Golden Jubilee; 60 years is a Diamond Jubilee. Generally speaking the longer the period, the more precious the material associated with it. Those of nations usually by the number of years elapsed in Latin.
