From B-Side To Smash Hit: 9 Classic Rock Songs That Defied Expectationss
via screenrant.com
Short excerpt below. Read at the original source.
Before the days of Spotify, when people used to buy records on vinyl from a music store, albums were released very differently than they are today. The promotion was similar, though promotion via word-of-mouth was much more literal, and singles were still released prior to the albums to give fans a little taste.