Developers have been toying with the beta of OS X Yosemite since Apple announced the operating system at WWDC in June. Unfortunately for the rest of us, we have to wait (im)patiently until Yosemite launches officially this fall. Unless you signed up for Apple's public OS X Yosemite beta program, in which case tomorrow is your lucky day.
OS X users who sign up for this program, which was also announced at WWDC, get access to the beta early without needing a developer account. And beta access will ship Thursday, July 24th.
Here's how it works. If you signed up with your Apple ID on the beta program website (it's still not too late to do so), tomorrow you will get an email with a link and activation code to download the latest Yosemite build. While developers get updates to their beta versions every two weeks or so, members of this public beta will only get a handful of updates until Yosemite launches in the fall, and users' versions will be brought up to speed with the final release version by that point. In other words, you won't have to wipe your system and re-install the final release when it's available---you'll already have it.
This isn't the first time Apple has opened up beta software to the public. Apple gave consumers access to the first beta version of OS X a decade ago (although it wasn't free). And in April, the company also opened its OS X Beta Seed program for Mavericks.
Before you download the release though, there are a few things you should do. First, backup your data. Before you download any major OS update, you want to backup your data just in case something goes wrong. Dropbox, iCloud, and Google Drive are easy options for uploading important files and photos to the cloud, but you can also copy data to a USB drive if you'd rather have a local hard copy.
Next, if you have the luxury of owning multiple Macs, download the beta onto your secondary machine rather than your main workhorse. Yosemite is still a beta, and it can (and will) have bugs from time to time. Your life might be a bit easier if those bugs don't pop up when you're halfway through an important project at work. If you do discover a bug, or have feedback about the OS X build as you're using it, Apple has built in a feedback assistant app so you can swiftly and easily send your thoughts to Apple. Will Apple read all your feedback? Theoretically, yes. Will it implement your grand idea for a better system-wide font choice? Probably not.
The OS X Beta program is free and open to anyone with an Apple ID, but right now it's capped at one million users. Downloading the software won't void the warranty on your current machine, and if you decide you don't want to use a beta of Yosemite after all, Apple will provide detailed information about how to revert back to Mavericks.
