Melody of "Happy Birthday to You" (also known as the "birthday song") written in 1890 by an American woman by the name of Mildred Hill.
Originally sister Patti, who is a teacher, put the words "Good morning my teacher, I hope this is a good morning to you" in order to fit the melody. The song was eventually popular over the years and sung in schools across the U.S..
Forty years later, it is believed that Patti replace with the words "Happy Birthday, Happy Birthday, Happy Birthday Dear Happy Birthday to You", which became very famous.
The entire song and then published in 1935. The song was later popularized in 1930, when it was sung in the Broadway production "As Thousands Cheer" and has since become a mega-hit all-time classic.
The news of interest: The song "Happy Birthday to You" (lyrics and melody) is still under copyright protection, so that every time you hear it sung on TV or radio, royalties are still paid to the publisher (Warner Chapel, in the U.S.).