The use of the term album in regards to recorded music came about in the early 1900s when music pressed onto a shellac compound was packaged in a book form, similar to a photograph album. This was to protect the fragile discs and continued when, in 1948, vinyl became the material of choice by manufacturers.
In the 1960s these covers took off as a form of art all on it's own. The Beatles, The Rolling Stones and The Grateful Dead are just three of the many groups that upped the game in how these album covers were received. And despite the fact that, with the prevalence of CDs, the size of the packaging has gotten much smaller the artwork is still considered be an important part of the total end result.
But what to call our modern day CDs, mp3s, steaming audio files, or other digital forms that have taken the place of vinyl discs, 8-tracks, and cassette tapes?