Contains a read-only hash table (Constant, AllScope) that displays details about the version of PowerShell that is running in the current session.

$PSVersionTable    #this call results in this:
Name                           Value
----                           -----
PSVersion                      5.0.10586.117
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.10586.117
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1

The fastest way to get a version of PowerShell running:

$PSVersionTable.PSVersion  
# result :
Major  Minor  Build  Revision
-----  -----  -----  --------
5      0      10586  117