Birthday" is a song by English singer Anne-Marie. She co-wrote the song with Delacey, Keith Sorrells and Warren Felder. It was released as a single on 7 February 2020.
In an interview when she was on Sunday Brunch, she said the song reflects the happiness she is feeling at the moment, "Do you know what, I've written a lot of songs about being angry at my exes, which I think I'm quite known for so when I went into this new album I was like 'Do you know what, I'm happy at the moment, this song kind of shows that I think". She also explained, that around October 2019, she heard many Christmas songs and noticed, that there are only a few versions of Birthday songs, so she decided to make her own.