Patty Hill was a kindergarten principal in Louisville, Kentucky, developing various teaching methods. Her sister Mildred was a pianist and composer. The sisters used "Good Morning to All" as a song that young children would find easy to sing. The combination of melody and lyrics in "Happy Birthday to You" first appeared in print in 1912, and probably existed even earlier.

The Summy Company registered a copyright in 1935, crediting authors Preston Ware Orem and Mrs R. R. Forman. In 1988, Warner/Chappell Music purchased the company owning the copyright for US$25 million, with the value of "Happy Birthday" estimated at US$5 million. Based on the 1935 copyright registration, Warner claimed that the United States copyright will not expire until 2030 and that unauthorized public performances of the song were illegal unless royalties are paid to Warner. In one specific instance in February 2010, the royalty for a single use was said to be US$700. By one estimate, the song is the highest-earning single song in history. In the European Union, the copyright for the song expired on January 1, 2017.

In September 2015, a federal judge declared that the Warner/Chappell copyright claim was invalid, ruling that the copyright registration applied only to a specific piano arrangement of the song, and not to its lyrics and melody. In 2016, Warner/Chappell settled for US $14 million, and the court declared that "Happy Birthday to You" was in the public domain.

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