Birthdays are celebrated a bit differently in Germany than they are in the United States. Firstly, it's thought of a bad luck to wish someone a 'Happy Birthday' or give a card or present before the actual day. So, just to be on the safe side, many Germany wait until after the day has passed to send cards and presents. In Germany you are also expected to throw the party for yourself. You invite everyone to your house or to a restaurant where you cook or pay for everyone else.