PowerShell Core 6.0 is a new edition of PowerShell that is cross-platform (Windows, macOS, and Linux), open-source, and built for heterogeneous environments and the hybrid cloud.
From the Microsoft Blog
First and foremost, thank you to all of our amazing community, especially our open-source contributors (the most recent of which you can find on our community dashboard at https://aka.ms/PSGitHubBI) for donating your time and energy to PowerShell Core. Whether you contributed code, tests, documentation, issues, or even just your feedback and opinions, we are extremely grateful for the sweat and tears that you’ve invested in PowerShell. (For those interested in contributing, hop and over to our Contribution Guide on GitHub. You don’t have to be a guru to help out!)