The NY Times uses both "on Mac OS X" and "in Mac OS X". Can someone explain which one seems more appropriate if there is no difference?


2 Answers 2


To me, at least, "on Mac OS X" refers to things that run on top of Mac OS X, while "in Mac OS X" refers to things that are part of Mac OS X.

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    +1. On Mac OS, MS Word does such-and-such. In Mac OS, memory is managed by thus-and-such. Commented Jan 31, 2012 at 15:36

In computer terminology, "on" typically refers to things that involve a "platform":

I sell my music on Amazon.

My website is on the World Wide Web.

"In" will refer to specific programs, stores or components:

I sell my music in the iTunes store.

To open a file in Excel...

The confusion around Mac OS X is that it qualifies as both a platform and a specific piece of software depending on context:

My application runs on Mac OS X.

To delete a file in Mac OS X...

So the correct answer is that it depends on the specific usage. David Schwartz's answer provides a good rule of thumb for determining which usage is correct in a given scenario.


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