"Hoch sollst du leben, hoch sollst du leben, dreimal hoch …" (For he's a jolly good fellow) is how the German song goes. Germans celebrate their birthdays with family and friends. And gifts, a cake, and candles should definitely be a part of it. But birthdays are not the only important family celebrations.
The birth of a child is a reason for families to celebrate, but not necessarily a reason to throw a party. However, it's still common to give the new parents and/or the new baby a gift. One reason for a major celebration in Christian families is the baptism that follows, when a child is welcomed into its religious community.
The first day of school is also a major event and is celebrated. Children receive a "Schultüte", a big coloured cone that's decorated and filled with candy.
Depending on the religion, there is a series of religious rites of passage, such as First Communion and Confirmation. In non-Christian families, youth initiation ceremonies are sometimes celebrated. The young people often receive money on these occasions. The 18th birthday is a major one in Germany: it's often cause for a big celebration, and young people are then considered adults.
Graduation from school, college, or professional training is not necessarily a reason for a big celebration within the family, but it's often cause for a party among friends.
Weddings, on the other hand, prompt huge celebrations with many guests. This is probably also the case in your country.
Many couples get dressed up in elegant wedding dresses and suits for a civil ceremony at the registry office or in a church, then celebrate in a restaurant or hall, and afterwards go on a honeymoon.