According to DigoPaul, the concept of anniversary comes from anniversarius, a Latin word. This is what is repeated every year (that is, it is annual).
Typically, the term is used with reference to the date on which an event is celebrated. For example: “Tomorrow we will celebrate our fifth wedding anniversary”, “We are organizing the celebrations for the company’s new anniversary”, “Today marks the second anniversary of the terrible terrorist attack”.
The birthday, which refers to the day of birth of an individual, is the most popular anniversary. When a person turns 56, to cite a case, they celebrate the 56th anniversary of their birth. With each passing year, you will celebrate a new birthday / anniversary.
As a curious fact, although it is correct to use the term anniversary as a synonym of birthday from an academic point of view, in everyday speech the latter is the most common, while the former is usually used by those people who do not like to admit that they are also victims of the passage of time, that is, they age.
In this sense, saying “today is my anniversary” seems to be less graphic or direct than “today is my birthday”, since instead of focusing on the passage of time it refers to a celebration. However, if we review the etymology of the term, the decision seems absurd, since, as mentioned in the first paragraph, it speaks to us of “something that comes back every year”.
It is also common for the wedding anniversary to be celebrated. As its name suggests, this celebration commemorates the date in which a couple contracted marriage. The different anniversaries bear special names and link the celebration to one element: the third anniversary is called “leather weddings”, the fifth anniversary is known as “wooden weddings”, etc.
Currently, the general perception is that couples last less than in the past, that the percentage of separations and divorces has increased considerably in recent decades. As a consequence, it is no longer so common to reach the special anniversaries mentioned in the previous paragraph, much less the highest, such as the “pearl weddings” (at thirty years of marriage), the “ruby weddings” (at the age of forty), the “golden anniversary” (at the age of fifty), much less the “wedding of bone”, almost impossible to achieve even in the absence of divorce since they celebrate the hundred years of union in marriage.
On the other hand, there are those who stay together for fear of separating, or for different interests, and see the different anniversaries passing one by one without deserving them, so to speak, or without feeling them genuinely, as if they were trophies obtained illegitimately.
In each country, anniversaries of the most important events in their history are generally celebrated. The anniversary of the declaration of independence, the anniversary of a military triumph and the anniversary of the restoration of democracy are some of the most remembered ephemeris.
Depending on the culture, there may be a rejection of the youngest for learning these dates, either for focusing on other countries or for lack of interest in history; In any case, the fault is always found in education, in the perspective that is given to children about these issues, generally taking them to the extreme of patriotism or anti-nationalism.
The founding of a company, a sporting triumph, the passing of a law and the inauguration of an infrastructure project are other events that are usually remembered each year through its anniversary.