The Happy Birthday Song is a popular song. People around the world sing this song on their birthdays，but do you know the story behind the song？
In 1983，Mildred Hill，a teacher from America，wrote a simple tune（曲调） and her younger sister Patty added the lyrics（歌词）. They called it Good Morning to All. Every morning，teachers sang this song to the children as a welcome song in the class. When it came out，children across the United States loved this song very much，and they sang it to their teachers every afternoon when they left school.
Later，Robert H. Coleman added a second part to the song was the now famous Happy Birthday Song. His second part made the song much more popular. Over time，the sisters first part disappeared（消失）. The Happy Birthday song became the one and only birthday song. Now people from all over the world like it very much and sing this song in many languages on their birthdays. The languages can be different，but the happiness is the same.
