iTunes 1.0 — Beginnings
The first, and lesser-known, icon appeared on Mac OS 9 when iTunes 1.0 made its debut. Apple heavily marketed iTunes as a digital jukebox that can be used to rip and burn audio CDs—the prevalent music distribution format at the time. This made the CD an obvious choice for the icon, with the addition of three colorful eighth notes to spice things up. With less than 4 months in service, this was the shortest-lived iteration.
iTunes 1.1.1 — Perspective
The second iteration was released shortly after the initial release of OS X, but before iTunes added support for the new OS. The CD gained more details—notably the translucent plastic hub—and bid farewell to the straight-on perspective it originally shipped with. The notes got a visual upgrade as well, expanding in size and scoring more highlights and reflective shadows. These changes added a touch of realism to the icon and made it look sharper and more modern than the previous take.
iTunes 2.0 — Hello, OS X
This icon was introduced when iTunes made the jump to OS X in its second major version, which was timed with the release of the iPod. The colorful notes were replaced by a single beamed eighth note coated in a stern navy blue and casting a more visible reflection on the CD. Changes to the CD were relatively minor, with the most notable one being the less translucent plastic hub.
iTunes 3.0 — Goodbye, OS 9
In its third major release, iTunes dropped support for Mac OS 9. On the icon front, the note reverted to a purple hue reminiscent of the one used in pre-OS X versions, and traded the CD reflection for more reflective shadows, especially on the heads. The CD itself regained some of its pre-2.0 hub translucency and was given a less banded gradient.
iTunes 4.0 — Green
Another year, another color. This time, the vibrant purple was replaced by an equally vibrant green, perhaps a harbinger of the huge commercial success of the then newly-released iTunes Store. Within the same year, iTunes 4.1 added Windows XP support, making this icon the first to make an appearance on a non-Mac platform.
iTunes 7.0 — The Calm
With four years sitting in our docks, this is indisputably the most memorable and iconic version in this timeline. Apple went back to blue as a note color—albeit a brighter hue—and made the note heads rounder and less slanted. The note also gained a glossier finish as a result of toning down its reflective shadows and cranking up its highlights. As for the CD, the plastic hub lost most of its transluency, while additional color stops made the angle gradient on the surface look more detailed than ever.
iTunes 10.0 — The Storm
The most radical, and thus controversial, icon redesign in the history of iTunes. To celebrate the prevalence of digital downloads over physical media, the realistic-looking CD of yore was shown the door and a simplistic circular icon took its place. The note itself shrank in size and turned dark gray, with an outer glow serving to improve contrast against the blue background. A highlight was used in the top half of the icon to give it a glossy finish not dissimilar from the one used in iOS icons back then.
iTunes 11.0 — Cloud White
The musical note turned white, a color choice that was possibly a nod to the tighter iCloud integration that shipped in this version. Alongside this change, the note shrank even more—perhaps to better fit inside the circle—and lost its outer glow in favor of a not-so-subtle drop shadow. Meanwhile, the elliptic icon highlight became rounder and subtler towards the center.
iTunes 12.0 — Reunion
In the spirit of the desktop-mobile unification theme that Yosemite championed, this icon was the first to match its iOS Music counterpart in terms of palette and composition details. A bright salmon-pink gradient was used as a background and all shadows and highlights were removed. The note went on a diet in this iteration and gained a solid footing thanks to its more rectangular heads.
iTunes 12.2 — Past Meets Future
The release of Apple Music brought with it arguably the most colorful iTunes icon since 2001. The purple, blue, and salmon-pink colors of the radial gradient are in many ways an homage to the rich history of the icon. Unlike previous iterations and other OS X icons, the note was carved out of a white foreground, letting the colorful background bleed to form the outer edge of the icon. The shape of the musical note was subject to a minor change that affected the size and angle of the heads.