The first beta for macOS 10.12 Sierra is now available - here's how to get it

Apple held its keynote for its annual Worldwide Developer Conference (WWDC) today, where the firm announced what's next for OS X. As the rumors indicated, OS X is dead. Long live macOS.

After the event, Apple offered developer betas for all of its operating systems. This is a guide for installing macOS 10.12 Sierra beta.

The installation process for a macOS (or OS X) beta is undoubtedly the easiest, but be warned. Early betas from Apple tend to be very unstable. They're not for the faint of heart, so if you want to wait for the public beta, expect that in the 'beta 3' timeframe, which will likely be about four weeks away.

Prerequisites

An Apple Developer license, which costs $99/year
A Mac that's newer than 2009. You can find the full requirements here.

Installing the beta

Head over to Apple Developer (if you haven't guessed, do it from your Mac).
Go to Develop -> Downloads.
Click the Download link next to macOS 10.12. It will open the Mac App Store where it will download.
Follow the onscreen instructions to install.

Rolling back and updating again

As mentioned earlier, the build might be a bit too unstable for your taste, so you may find yourself wanting to roll back. And once the beta gets a bit more stable, you may want to update again.

There are various ways to roll back, but for this purpose, we'll be using an Internet Recovery. Shut down your Mac and boot it up while holding Command-R.
NOTE: Make sure that you're on a recognized network.
Use the Disk Utility to erase everything.
Shut down and once again boot up while holding Command-R.
Your Mac will now download and install the version of OS X that came with your PC.
Once that's done, you can get El Capitan (or whatever you were using before) through the App Store under the Purchased tab.
You'll also now see macOS 10.12 under Purchased, so whenever you're ready to try it out again, that's where you can find it and install it.

Remember that you're installing this at your own risk. We certainly don't recommend installing it on your main machine.