The new One Direction, Ed Sheeran collaboration has the singer writing a single about the group's first loves, in "18."

The newest release from One Direction and Ed Sheeran, "18," is nostalgic, at least by the group's standards. The song talks about the loves of youth, which, in the case of Harry Styles and the gang, involves events of less than three years ago.

Ed Sheeran penned the track, a stripped down single with an acoustic guitar backing. Sheeran's influence can be felt in the tune, and especially in the lyrics: "I have loved you since we were 18/ Long before we both thought the same thing/ To love and to be loved."

The track is a teaser of sorts to the release of One Direction's upcoming album, "Four," to launch on November 17. The group's newest project is with Syco/Columbia Records (ew.com).

The One Direction and Ed Sheeran collaboration also teams up with other artists, including Paloma Faith and Coldplay's Chris Martin. The team of various artists signed up to record a cover of the 1984 single "Do They Know It's Christmas," a Band Aid original with the likes of Boy George, Bono, and George Michael originally participating.

Band Aid founder Bob Geldof was inspired by the courage of medical volunteers in West Africa in the fight against Ebola, and inspired to do a re-recording of the track, reportedly featuring popular artists from the past and present. The single will be available for download November 17, simultaneous with the new One Direction album's release.

The One Direction and Ed Sheeran collaboration was confirmed as early as July, where Sheeran mentioned working in several tracks in the new album. In an interview via Perez Hilton:

"I wrote a couple of songs when I was 17 that One Direction want for their next album. I'm going into the studio in August to produce the tracks for them."