Best Day of my Life Lyrics video

Taylor Swift and mother Andrea Swift on the red carpet at the 2007 CMT Music Awards.

Rick Diamond/WireImage

It's no secret Taylor Swift knows how to write a love song. But did you know her very best one is about her mom?

For this week's Throwback Thursday, we're looking back on a song that is likely very familiar to Swift fans, but for casual listeners, it's a hidden gem just waiting to be discovered. "The Best Day" - off her second album Fearless - talks about the incredible role her mom played for her throughout her life.

"'The Best Day' is a song that I wrote without telling my mom, " Swift explained at the time. "I wrote it in the summertime, and I recorded it secretly, too. I had this idea that I wanted to play it for her for Christmas. So when I got the track I synced up all of these home videos from when I was a little kid to go along with the song like a music video, and played it for her on Christmas Eve and she was crying her eyes out."

Swift eventually went on to share her homemade video for the song, although the track was never released as an official single. Check it out below, but fair warning if you're at work: You might tear up quite a bit.