If your computer came with Yosemite already installed on it, you can skip this appendix—for now. But if you’re running an earlier version of the Mac OS and want to savor the Yosemite experience, this appendix describes how to install the new operating system on your Mac.
If you’re new in these parts, you may be in for quite a shock: You can’t buy Yosemite in a box, or on a DVD. You’re supposed to download it from the Mac App Store.
There are some very attractive elements to the download-only system. For example, there’s no copy protection and no serial numbers to type in. There’s no cost to Apple for manufacturing or shipping, which may explain why Yosemite isn’t even $20 or $30, like its predecessors—it’s free.
Now there’s no disc to hunt down later, when you want to install OS X again (onto a new Mac, for example). And when you do need a copy again, you’ll download the latest version—10.10.3 or whatever it is—instead of having to install whatever updates have come out since you got your DVD.