Humans are prone to attach emotions to material world in some or the other way and celebrate it by heart or just for the sake of a moment of rest from the busy life they have.
In that include the celebration of all people, The cake, or sometimes a pastry or dessert, is served to a person on their birthday. In contemporary Western cultures, the birthday person blows out the candles on the cake after those celebrating have sung the birthday song.The service of a birthday cake is often preceded by the singing of "Happy Birthday to You" in English speaking countries, or an equivalent birthday song in the appropriate language of that country.