The Get-Item command is used to get an object represented by a path:

Get-Item  # The root container 
Get-Item .  # The current container 
Get-Item .. # The parent container 
Get-Item C:WindowsSystem32cmd.exe  # A leaf item 
Get-Item Cert:LocalMachineRoot      #A container item 

The Get-ChildItem command, which has dir and ls aliases, is used to list the children of the current item.

Neither Get-ChildItem nor Get-Item will show hidden files and folders by default. The following error will be returned for a hidden item:

PS> Get-Item $env:USERPROFILEAppData
Get-Item : Could not find item C:UsersSomeoneAppData.
At line:1 char:1
+ Get-Item $env:USERPROFILEAppData
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 + CategoryInfo : ObjectNotFound: (C:UsersSomeone AppData:String) [Get-Item], IOException
 + FullyQualifiedErrorId : ItemNotFound,Microsoft.PowerShell.Commands.GetItemCommand 

The Force parameter may be added to access hidden items:

PS> Get-Item $env:USERPROFILEAppData -Force

    Directory: C:UsersSomeone

Mode                LastWriteTime         Length Name 
----                -------------         ------ ---- 
d--h--       23/09/2016     18:22                AppData