Authors and musicians have one, certainly. This is the book you wrote seven years ago or the album from early in your career. The book keeps selling, spreading the ideas and making a difference. The album gets played on the radio, earning you new fans.
“Backlist” is what publishers call the stuff that got published a while ago, but that’s still out there, selling.
The Wizard of Oz, Bob Dylan’s Greatest Hits and Starsky and Hutch all live on the backlist.
Without a backlist, all book publishers would go out of business in no time. The backlist pays dividends long after the work is over.
Advertisers didn’t used to have a backlist. You paid for that magazine or newspaper or TV ad, and within just one cycle, it was gone, forever.