When Paul McCartney laid down the demo for “Yesterday,” he didn't intend for the song to stay so spare—but in the end, the other Beatles couldn't figure out what to play without getting in the way. Point being that even if you're going full-band, there's something about an unplugged arrangement that allows the heart of a song to shine. Spanning old and new, mellow to lively, this playlist showcases the acoustic (OK, mostly acoustic) side of pop: light, direct, and crystalline. Our editors regularly update these selections. If you like a tune, add it to your library.