PowerShell Snapins
Snapins in Powershell are like toolboxes, including many commands, specific to a tool, a software, etc..
The two most important (most famous) :
Microsoft.Exchange.Management.PowerShell.Admin
VMware.VimAutomation.Core
Here is the command to add a snapin :
Add-PSSnapin
A really easy way to add all installed snapins :
Get-PSSnapin -registered | Add-PSSnapin