Name Day is in calendars around the world the feast day of the saint after whom a person is named at baptism.
In early centuries, Christians began honoring the first saints - also known as martyrs - who were slain for their faith.
Each year, on the anniversary of the martyr's death, Christians celebrated the day as a feast day, the martyr's birthday, into heaven.
It was more of an occasion of rejoining, rather than a day of mourning.
Over time, it became customary to adopt or to give saints' names to children at baptism, particularly the name of a patron saint, a special protector and guardian in heaven who would look after the child throughout his or her life.
However, throughout the centuries many other names that appeared in the Bible, other than saints, also began to appear in calendars, in addition to those of many kings (particularly in Scandinavian countries) and national heroes (Ancient Greek Gods), resulting in saints' names starting to be considered as equal with names of common people.
This, in combination with Martin Luther's Reformation in sixteenth century, put name days celebration in Catholic countries out of the picture.
In Orthodox countries, on the other hand, such as Greece and Russia, the celebration of name days is still very vivid nowadays, particularly because of a totally different tradition and different bonds between the Church and the society.
After all, it is our first names' little birthday, which are anyway one of the more important possessions we have in life!