Test-Path is highly useful to test whether a file or folder exists, and it can be used with any of the PowerShell drives, so it can also test whether a variable, a function, or a certificate exists (for example).
In recent PowerShell versions, Test-Path can now differentiate between containers (i.e. folders) and leafs (i.e. files), too:
$path = 'c:\windows\explorer.exe' # any item type Test-Path -Path $path # just files Test-Path -Path $path -PathType Leaf # just folders Test-Path -Path $path -PathType Container