"18" is a nostalgic acoustic-driven ballad from One Direction's 2014 album, FOUR , which was written by Ed Sheeran and explores enduring love from a young age. The song, which features a notable chorus about loving someone since they were 18, is known for its intimate feel and a bridge often associated with Niall Horan's vocals. Ed Sheeran and Oliver Frank wrote the track, with production handled by Julian Bunetta, Pär Westerlund, and John Ryan.