Q: Why, even though no module was loaded in my Windows 8 and Windows Server 2012 PowerShell session, did a cmdlet from the module still work?
A: Typically to use cmdlets from a module, that module must be imported into the current PowerShell session using the Import-Module cmdlet. And that's still a good practice to explicitly load the modules you need in your session. However, PowerShell 3.0, which is part of Windows 8 and(but is also available for older OSs) features a new auto-loading capability of modules.
This is likely what you are seeing if cmdlets from modules not loaded "just work". The new functionality works by automatically scanning all the modules in your default path for commands.
If it comes across a command it doesn't know, and if it finds a match, then that module is automatically loaded and used. This also works for custom scripted modules (psm1) you may have created. Below is this behavior in action using my own Send-Wakeup function I mentioned in a previous FAQ.
First, I look at the modules I have loaded.
I can see I have three modules loaded.
Now I try to run a cmdlet from a module I haven't loaded:
PS C:\> Send-Wakeup savdalhv01
Wake-On-Lan magic packet sent to 00:15:17:C4:E1:05, length 102
It just worked. If I look again at the modules loaded, I see my custom module was automatically loaded when my PowerShell session found I didn'tt have a module loaded with the command I entered. It went out and found a match and loaded it automatically.
This demonstrates the new autoimport functionality in PowerShell 3.0. However, I still think it's a better option to manually load the modules you want to use, as it gives you more control over the actual module being used. Sometimes it might happen that two different modules could have a cmdlet with the same name and might therefore give unexpected results.
You might also look at "Q: How can I have a certain PowerShell module always load when I start PowerShell?"