PowerShell has gone through a number of versions since it was first released in November 2006. These are the major features of the PowerShell versions:
PowerShell v1 – initial release with 137 cmdlets. (released with Windows Vista / Server 2008 – not Server Core). Only way to work remotely was Get-WmiObject. no longer available.
PowerShell v2 (Windows 7 / Server 2008 R2) – introduced PowerShell remoting, PowerShell jobs and extended WMI cmdlets. Deprecated.
PowerShell v3 (Windows 8 / Server 2012) – Workflows, CIM cmdlets
PowerShell v4 (Windows 8.1 / server 2012 r2) – DSC
PowerShell v5 (Windows 10) – PowerShell classes
PowerShell v5.1 (Windows 10 Update / Server 2016) – mainly bug fixes for v5
PowerShell v6.0 (open source) – SSH remoting, installs for Linux and mac
PowerShell v6.1 (in development) – mainly fixes and updates to v6.0
Documentation has become weaker over time and is currently available from – https://docs.microsoft.com/en-gb/powershell/scripting/powershell-scripting?view=powershell-6
Which version should you use?
If you’re on Windows use the version installed OR download and install the latest WMF package for your version of Windows. PowerShell v6 is useful for non-domain remoting or remoting to Linux servers.
If you’re on Linux or mac the your only choice in v6.x