PowerShell is a very complex language, with subtle nuances that can trip up even the most experienced programmers.
This site aims to document these dark corners of the language by running real example code against all PowerShell versions and displaying the results. The documentation is kept up-to-date by downloading all release versions of PowerShell Core each time the site is generated, and running examples against those versions as well as against Windows PowerShell 5.1 and 2. Users should be confident that if they were to run the examples on their own computers, the output would be the same (although at the moment that isn't always the case).
If you know of a PowerShell quirk which is missing from this site, please feel free to create an issue or open a PR at https://github.com/benweedon/pwsh-live-doc/. Please also see https://github.com/nightroman/PowerShellTraps/, which is itself an incredible store of PowerShell knowledge this site makes heavy use of.