Similarly, once you've installed the public beta, make sure not to entrust any important data to only your test Mac or drive. Multiple copies of important data are, as always, a good idea.
How do I install the Yosemite beta?
You'll install the Yosemite beta just as you would Mavericks: You download the installer from the Mac App Store, double-click the downloaded installer app, choose a volume on which to install, and follow the prompts.
Of course, that's the oversimplified version. If you've read our installation guide for Mavericks, you know that there are a few things you can do to help ensure the process goes smoothly, such as first using Disk Utility to check the drive you'll be using for the beta, and making sure you have the latest versions of your favorite apps. Some developers may even have beta versions of their own software that have been updated for use with the Yosemite beta.
You can then follow along with our Mavericks installation article, as the procedure is nearly identical. As mentioned above, we recommend dedicating a separate Mac, or at least a separate drive or partition, for Yosemite beta testing.
One suggestion mentioned in that guide that I want to call out here: If the Yosemite beta installer is located in its default location (in /Applications), the installer will delete itself during the installation process. So if you'd like to keep the installer application around--say, for creating a bootable installer drive (a procedure we'll be explaining for you soon)--you'll need to keep a copy of it somewhere outside of your main Applications folder.
Will Apple provide updates to the Yosemite beta like it does regular versions of OS X? Do I have to update?
Yes, over the course of the beta program, Apple will provide periodic updates to the OS. These will be available, as with updates to Mavericks, through the Mac App Store. It's a good idea to update, so you know you're running the latest version of the Yosemite beta, though you won't be required to update.
(Normally, we'd recommend waiting a few days after an OS update is released so you can watch for reports of major bugs, installing once it seems as though the update is solid. However, as the point of a beta test is to test, and as you're not running the beta OS on your primary Mac--right?--and as you're making extra-extra sure your data is safely backed up, you should probably just update immediately.)
What if I install the Yosemite beta and regret it? Can I go back to Mavericks?
Unlike with iOS, you can always revert to an earlier version of OS X, though depending on how you back up, it's not necessarily a painless process.
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