Microsoft has done a great job is providing documentation about PowerShell. Here’s two important links:
1. PowerShell Language Specification Version 2.0 at: http://www.microsoft.com/en-us/download/details.aspx?id=9706
2. PowerShell Language Specifiction Version 3.0 at: http://www.microsoft.com/en-us/download/details.aspx?id=36389
It’s good reading material.
Thank You Microsoft!