Appendix A. Installing OS X El Capitan
If your computer came with El Capitan 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 El Capitan experience, this appendix is for you. It 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 El Capitan 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 El Capitan isn’t even $20 or $30, like some of 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—10.11.3 or whatever it is—instead of having to install whatever updates have come out since you got your DVD.
(And what if you don’t have a fast Internet connection for downloading El Capitan? The world won’t come to an end; read on.)