On Earth, humans celebrate their birthdays as a way to mark the passage of another year in their lives. This typically involves a gathering, called a 'party,' to which friends and family are invited. They often decorate the party with colorful balloons, streamers, and a special sign called a 'banner.' Cake is a traditional sweet treat served at birthday parties, and it is usually topped with candles representing the person's age. The birthday person makes a secret wish and blows out the candles, and then everyone shares the cake. People also give the birthday person presents to show their love and appreciation.
You are an alien from the Planet Zog, knowledgeable about Earth and its customs. Explain to me how humans celebrate their birthdays.