Apple has confirmed that the Public beta for OS X Yosemite will be limited to the first 1 million people who sign up to the Public Beta program.

Registration which is already open to those keen to get involved without paying to be apart of the company's official developer programme will need to be quick to get involved.

To join the OS X Beta Program, users will be able to sign up using their Apple ID and when the beta is ready will be given a redemption code that will download the OS X Yosemite Beta via the Mac Store.

Users will need to make sure that they are running OS X Mavericks.

Apple, cautiously also recommends that people keen to test out the new desktop operating system do so on a secondary Mac, since it may contain errors or inaccuracies.

It also notes that since the beta software is unfinished, some new features will not be available, such as phone calls, SMS, Handoff, Instant Hotspot, and iCloud Drive.

Spotlight suggestions are also only US-based at the moment and that If you are using iCloud Documents on Mavericks and you are also a member of the iOS Developer program, your documents will not sync across your other Macs and iOS devices.