Ipad Mini

Image source: Apple.

In no uncertain terms, Apple (NASDAQ:AAPL) has been instrumental in launching the mobile revolution. Consumers use mobile devices in ways they never could have dreamed of a decade ago, and the rise of mobile platforms created incredible new opportunities for many industries as the PC market matured.

This was all made possible by the creation of iOS, which powers Apple's mobile devices. When iOS was being developed, Apple executives debated whether they should start with the iPod operating system and build it up to handle more powerful devices. The alternative was to take Apple's existing desktop platform, OS X, and strip it down to the basics to achieve the same goal. The company went with the former. iOS devices now drive the majority of Apple's sales, well beyond the revenue that Macs and OS X bring in.

While the iPod Touch also runs iOS, Apple has never explicitly broken out iPod product mix and disclosed unit volumes for the iPod Touch. The Mac maker used to often say that over half of all iPod units sold each quarter were iPod Touches, which is strategically significant as a sort of gateway product into the iOS ecosystem. But lacking concrete data around iPod Touch units, we'll focus on the iPhone and iPad.

As of the most recent quarter, Apple has sold over 1.1 billion iOS devices to date (not including the iPod Touch).

Here's a breakdown of iPhone and iPad units since 2013.

Quarter

iPhone and iPad Units

Cumulative Lifetime Units

Q1'13

56.9

496.8

Q2'13

45.9

542.7

Q3'13

47.7

590.5

Q4'13

77.1

667.6

Q1'14

60.1

727.7

Q2'14

48.5

776.1

Q3'14

51.6

827.7

Q4'14

95.9

923.6

Q1'15

73.8

997.4

Q2'15

58.5

1,055.9

Q3'15

57.9

1,113.8

Data source: SEC filings. Unit figures in millions.

There is another way that iOS has been critical to Apple's product development. The operating system has also served as a foundation for Apple's other platforms. Both watchOS that powers Apple Watch and tvOS that powers Apple TV are based on iOS before they were tailored for different product categories.

Evan Niu, CFA owns shares of Apple. The Motley Fool owns shares of and recommends Apple. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.